Finely grate the zest from one lime. Reserve most of it for garnish and place about 1 teaspoon into a small bowl.
Add 1 tablespoon fresh lime juice, sliced red onion, 1/4 teaspoon sugar, and 1/4 teaspoon kosher salt. Toss well and let the onions pickle for at least 15 minutes.
Juice the remaining limes until you have about 1/4 cup of juice.
Whisk together the lime juice, garlic, chopped cilantro, olive oil, remaining sugar, and remaining kosher salt until smooth.
In a large serving bowl, combine butter lettuce, cucumbers, cherry tomatoes, peaches, and feta cheese.
Add the pickled onions, pumpkin seeds, reserved lime zest, and fresh cilantro.
Drizzle half of the dressing over the salad and gently toss to combine.
Finish with the remaining dressing, season with black pepper and additional salt if needed, and serve immediately. This Summer Salad Recipe tastes best when freshly assembled.