Wash and dry all produce. Adjust rack to upper position and preheat oven to 450 degrees. Trim and discard bottom woody ends from asparagus. Halve stalks lengthwise, then cut into 3/4-inch pieces. Zest, then halve lemon. Cut one half into wedges.

Place flatbreads on two baking sheets. Toast in oven until a light golden brown, 5-8 minutes. After removing from oven, preheat broiler to high.

Heat a medium pan over medium-high heat. Add pancetta and cook, stirring often, until crispy, 5-7 minutes. Remove from pan with a slotted spoon and set aside on a paper-towel-lined plate. Carefully pour out all but 2 tsp grease in pan.

Add asparagus to pan used for pancetta over medium-high heat. Cook, tossing occasionally, until tender and lightly browned, about 4 minutes. Season with salt and pepper. Remove pan from heat.

Spread pesto in an even layer over flatbreads, then scatter mozzarella, asparagus, and pancetta over top. Place one sheet with flatbreads under broiler. Broil until mozzarella is melted and beginning to brown, 2-4 minutes. Repeat with topped flatbreads on other sheet. TIP: Keep an eye out for any burning— broilers vary widely.

Meanwhile, toss lettuce in a large bowl with 2 TBSP olive oil and a squeeze or two of lemon (to taste). Season with salt and pepper. Cut finished flatbreads into slices, then sprinkle with lemon zest (you can skip this for the kids). Serve with salad on the side and lemon wedges for squeezing over.