In a medium bowl, whisk together the red wine vinegar, sugar, minced shallot, lemon juice, Dijon mustard, salt, and black pepper until the sugar dissolves and the shallots are evenly distributed. This creates an emulsion base that will hold the oil. Slowly drizzle in the olive oil while whisking constantly to create a smooth, cohesive dressing. The gradual incorporation of oil prevents the vinaigrette from breaking and ensures a creamy texture. Taste and adjust seasoning as needed. Divide the dressing in half—you'll use one portion to marinate the chicken and reserve the other for finishing the salad.

Place the pounded chicken breasts (they should be an even 3/4-inch thickness) in a bowl or zip-top bag and pour half of the vinaigrette from Step 1 over them, reserving the other half for later. Ensure the chicken is well coated, then refrigerate for at least 1 hour or up to 8 hours—this time allows the flavors to penetrate the meat and tenderize it slightly. While the chicken marinates, prepare your mise en place: halve the cherry tomatoes, chop the romaine into bite-sized pieces, dice the cucumber, slice the red onion thinly, and if using fresh corn, remove the kernels from the cob. I like to prep all my vegetables while the chicken marinates so nothing holds up the final assembly.

Heat your grill to medium-high heat (around 400°F if using a temperature gauge). Remove the chicken from the marinade, allowing excess dressing to drip off—don't pat it completely dry as some of the flavor should remain on the surface. Place the chicken breasts directly on the grill grates and cook for 5-6 minutes on the first side without moving them; this creates a nice char and grill marks. Flip once and cook for another 5-6 minutes on the second side until the internal temperature reaches 165°F. Once cooked, transfer the chicken to a cutting board and let it rest for 5 minutes—this allows the juices to redistribute, keeping the meat moist and tender.

After the chicken has rested, slice it against the grain into bite-sized strips or chunks. Place the chopped romaine lettuce in a large bowl or on a serving platter and drizzle with the reserved half of the vinaigrette from Step 1, tossing gently to coat evenly. The dressing will begin to soften the lettuce slightly while adding flavor. This base layer should be lightly dressed so the salad doesn't become soggy.

Arrange the sliced grilled chicken on top of the dressed lettuce, then distribute the halved cherry tomatoes, diced cucumber, corn kernels, thinly sliced red onion, crumbled bacon, and crumbled blue cheese evenly across the salad. Slice the avocado just before serving to prevent browning, then arrange the slices on top. Drizzle any remaining dressing over the entire salad or serve it on the side so diners can add as much as they prefer. I always keep the avocado separate until the last moment—even a few minutes of exposure to air can cause browning, so this timing is crucial for both appearance and texture.