Prepare the mango vinaigrette by adding the diced mango, garlic, lime juice, sweet chili sauce, rice vinegar, olive oil, kosher salt, black pepper, and a pinch of red pepper flakes to a food processor. Blend until smooth and creamy. Taste and adjust the seasoning if needed.
Preheat a grill or grill pan over medium-high heat.
Brush the chicken breasts with olive oil and season them with the remaining kosher salt and black pepper. Grill for 6 to 8 minutes on one side, then flip and cook for another 6 to 7 minutes, or until the chicken reaches an internal temperature of 165°F (74°C). Transfer to a cutting board and allow the chicken to rest for several minutes before slicing.
In a large salad bowl, combine the mixed greens, sliced mango, red bell pepper, red onion, and half of the chopped mint, cilantro, and basil.
Pour most of the mango vinaigrette over the salad, reserving about ¼ cup for serving. Toss gently until everything is evenly coated.
Arrange the sliced grilled chicken over the salad. Add the sliced avocado, remaining fresh herbs, and chopped roasted peanuts.
Finish by drizzling the reserved mango vinaigrette over the top before serving