Start by prepping all your fresh ingredients with clean, dry cutting boards and sharp knives. Chop the romaine hearts into 1-inch pieces, dice the cucumber into 1/2-inch cubes, seed and chop the tomatoes into 1/2-inch pieces, and dice or thinly slice the apple. I like to prep the apple last and toss it lightly with a splash of the vinegar to prevent browning—this also gives it a subtle flavor boost. Place all prepped vegetables and fruit into a large serving bowl.

In a jar with a tight-fitting lid, combine the olive oil, cider vinegar, apple juice concentrate, honey, and Dijon mustard. Seal the jar and shake vigorously for about 30 seconds until the dressing is well emulsified and the honey is fully dissolved. The mustard acts as an emulsifier here, helping the oil and vinegar stay together longer. Taste the dressing and adjust the balance—if it's too sharp, add a touch more honey; if it needs more tang, add another teaspoon of vinegar.

Pour the vinaigrette from Step 2 over the vegetables and fruit in the bowl, then add the crumbled feta cheese. Toss gently but thoroughly, making sure every piece is coated with dressing. Season with the salt and black pepper, then taste and adjust seasoning as needed. I find that adding salt and pepper after the dressing allows you to season more evenly since the feta already adds some saltiness. Serve immediately while the salad is fresh and crisp.