Tasty BLT Sandwich with Onion

If you ask me, the BLT is already a perfect sandwich.

But when you add sweet, caramelized onions to the mix, you get something that takes this classic to the next level. Crispy bacon, fresh lettuce, and juicy tomatoes pair with golden onions that bring a mild sweetness to every bite.

The onions cook down slowly in their own juices until they’re soft and slightly sweet. They add a new layer of flavor that works perfectly with the smoky bacon and fresh vegetables.

It’s a simple twist on a beloved sandwich that makes lunch feel a little more special.

What Kind of Bacon Should I Use?

For the best BLT, you’ll want to use thick-cut bacon rather than thin slices since it holds up better and gives you that satisfying crunch. Regular pork bacon is the classic choice, but turkey bacon works too if you prefer a lighter option. When cooking your bacon, aim for that perfect balance between crispy and chewy – not so crispy that it shatters when you bite into your sandwich, but cooked enough that it’s not floppy. If you’re cooking a lot of bacon at once, try baking it in the oven on a sheet pan at 400°F for more even results than pan-frying.

Options for Substitutions

This BLT sandwich is pretty straightforward, but here are some easy swaps you can make:

• Sourdough bread: Any sturdy bread works great here – try whole wheat, rye, or even a good white sandwich bread. Just make sure it’s thick enough to hold all the fillings without getting soggy.
• Bacon: Turkey bacon is a lighter option, or you could use ham or even crispy prosciutto for something different. Cook time will vary depending on what you choose.
• Deli turkey: Feel free to use ham, roast beef, or even leftover roasted chicken. You could also skip the meat entirely for a classic BLT.
• Cheese: Cheddar, Swiss, or provolone all work well. If you want something creamier, try avocado slices instead of cheese.
• Red onion: White or yellow onion work just fine, or you could use green onions for a milder flavor. If raw onion isn’t your thing, try caramelized onions instead.
• Mayo: Mustard, avocado spread, or even ranch dressing can replace mayo. You could also use a mix of mayo and mustard for extra flavor.
• Butter: Olive oil or cooking spray work for toasting the bread, or you can skip this step entirely if you prefer untoasted bread.

Watch Out for These Mistakes While Cooking

The biggest mistake when making BLT sandwiches is using watery tomatoes, which will make your bread soggy and ruin the whole sandwich – always choose firm, ripe tomatoes and pat them dry with paper towels after slicing.

Another common error is not toasting the bread properly, so make sure to butter both sides and toast until golden brown for the perfect crunch that holds up against all the fillings.

Don’t forget to cook your bacon until it’s crispy but not burnt, and drain it on paper towels to remove excess grease that could make your sandwich messy.

For the best results, slice your red onion paper-thin using a sharp knife or mandoline, and assemble your sandwich just before serving to keep everything fresh and prevent the bread from getting soggy.

What to Serve With BLT Sandwich?

A classic BLT sandwich pairs perfectly with crispy potato chips or homemade fries – there’s something about that salty crunch that just works with the smoky bacon and fresh tomatoes. I love serving mine with a simple side of coleslaw or a light cucumber salad to balance out all those rich flavors from the bacon and mayo. If you want something warm, a cup of tomato soup makes for great dipping, especially since you’ve already got those beautiful tomato slices in the sandwich. For a lighter option, try some fresh fruit like watermelon or grapes, which taste amazing alongside the savory bacon and turkey.

Storage Instructions

Best Fresh: BLT sandwiches are really best enjoyed right after making them since the bread can get soggy from the tomatoes and mayo. If you need to save one for later, wrap it tightly in plastic wrap and keep it in the fridge for just a few hours max.

Prep Ahead: Here’s what I do when I want to make these ahead – I keep all the components separate! Cook the bacon and store it in the fridge for up to 5 days, slice your tomatoes and onions the morning you plan to eat, and keep everything in separate containers. Then just assemble when you’re ready to eat.

Pack Smart: If you’re packing this for lunch, try the ‘inside-out’ method – put the mayo and wet ingredients like tomatoes between the meat and cheese instead of directly on the bread. This helps create a barrier so your bread stays nice and crispy until you’re ready to dig in.

Preparation Time	10-15 minutes
Cooking Time	5-10 minutes
Total Time	15-25 minutes
Level of Difficulty	Easy

Estimated Nutrition

Estimated nutrition for the whole recipe (without optional ingredients):

• Calories: 1800-2000
• Protein: 80-90 g
• Fat: 110-125 g
• Carbohydrates: 120-135 g

Ingredients

For the sandwich:

• 8 tomato rounds (cut into 1/4-inch thick slices)
• 4 slices cheese (cheddar or provolone work well)
• thin red onion rings (sliced paper-thin, about 1/8-inch)
• 4 lettuce leaves (crisp romaine or iceberg preferred)
• 8 slices turkey breast lunch meat (I use Boar’s Head)
• 12 strips cooked bacon (crispy, about 1/4-inch wide)
• 8 slices sourdough bread (toasted lightly for structure)

For assembly:

• mayonnaise (room temperature for easy spreading)
• 4 tbsp butter (softened for toasting bread)

Step 1: Prepare and Assemble Sandwich Ingredients

• 8 slices sourdough bread
• 8 tomato rounds
• thin red onion rings
• 4 tbsp butter

Lay out all your ingredients in an organized workspace.

Ensure the bacon is already cooked and crispy, the mayonnaise is at room temperature for easy spreading, and the butter is softened.

Lightly toast the sourdough bread slices to give them structure that will hold up to the moist fillings without becoming soggy—this is essential for a great sandwich.

Slice the tomatoes into 1/4-inch thick rounds and slice the red onion paper-thin (about 1/8-inch).

I like to soak thin onion slices in ice water for 5 minutes before using them; it mellows their bite and adds a crisp texture to the sandwich.

Step 2: Build the Sandwich with Mayo and Fillings

• 2 slices toasted sourdough bread
• mayonnaise
• 4 lettuce leaves
• 8 tomato rounds
• thin red onion rings
• 8 slices turkey breast lunch meat
• 12 strips cooked bacon
• 4 slices cheese

Spread mayonnaise generously on the inside of two toasted sourdough slices—this creates a flavorful base and helps seal the bread against moisture from the tomatoes.

On one slice, layer the fillings in this order: lettuce leaf first (acts as a moisture barrier), then tomato slices, then paper-thin onion rings, then turkey slices, and finally the crispy bacon strips.

Top with one slice of cheese.

The order matters here—softer items go on the mayo, then structural items layer on top to create a stable stack.

Step 3: Butter and Toast the Sandwich

• assembled sandwich from Step 2
• 4 tbsp butter

Preheat a griddle or large skillet to medium-high heat (around 375°F).

Spread softened butter on the outside of both bread slices of your sandwich.

Place the sandwich butter-side down on the hot griddle and cook for 3-4 minutes until the bread becomes golden brown and crispy, which will also help melt the cheese through gentle heat conduction.

The cheese will begin softening as the sandwich heats.

I like to press down gently with a spatula midway through cooking to ensure even contact with the griddle and help the cheese melt more evenly.

Step 4: Flip and Finish Cooking

• sandwich from Step 3

Carefully flip the sandwich using a wide spatula and cook the other side for 2-3 minutes until it’s equally golden and crispy.

The cheese should now be fully melted and the sandwich heated through.

Both sides should have a crispy, golden-brown exterior that provides textural contrast to the soft, flavorful interior.

Step 5: Slice and Serve

Transfer the finished sandwich to a cutting board and slice it diagonally in half—this not only makes it easier to handle and eat, but it also creates a more attractive presentation.

Serve immediately while the sandwich is still warm and the cheese is melted.