Place the chicken breasts in a bowl, baking dish, or a resealable bag for marinating.
Combine 1/4 cup cilantro, 3 tablespoons lime juice, 1 1/2 tablespoons honey, 2 minced garlic cloves, 1/4 teaspoon salt, 1/4 teaspoon pepper, a pinch of crushed red pepper flakes, and 1/3 cup olive oil in a blender and blend until smooth.
Pour the marinade over the chicken, seal or cover, and refrigerate for at least 30 minutes and up to 2 hours.
While the chicken marinates, make the peach pico de gallo: in a bowl combine 1 cup chopped cherry tomatoes, 1 diced peach, 1 diced shallot, 1 seeded and diced jalapeño, 3 tablespoons chopped cilantro, juice of 1 lime, and a pinch of salt and pepper; stir to combine. Chill or let sit 10–15 minutes to meld flavors.
Preheat a grill (or grill pan) to high heat for at least 10 minutes until about 500–550°F if using a thermometer.
Remove chicken from the marinade and let excess drip off. Grill the chicken 5–6 minutes per side, or until an instant-read thermometer inserted into the thickest part reads 165°F.
Transfer the chicken to a cutting board and let rest 5 minutes, then slice and serve topped with the peach pico de gallo.