A turn on the classic combination of peas and mint, this vibrant salad intersperses whole leaves among spring greens, while torn leaves invigorate the lemon vinaigrette.
Place lemon juice in a small bowl. Add oil in a slow, steady stream, whisking until emulsified. Tear 1/3 cup mint into small pieces, and add to vinaigrette. Let stand at room temperature for 1 hour.
Cook pancetta in a skillet over medium heat, turning once, until crisp, about 10 minutes. Drain on paper towels.
Strain vinaigrette through a fine sieve into a small, clean bowl, pressing on mint to extract liquid.
Toss together pea shoots, mesclun, and remaining whole mint leaves in a bowl, and arrange on serving plates. Drizzle vinaigrette over greens. Season with salt and pepper, and serve immediately with the pancetta on the side.