In a food processor or blender, combine the diced mango, garlic, lime juice, sweet chili sauce, rice vinegar, olive oil, salt, black pepper, and red pepper flakes. Blend until smooth to make the mango vinaigrette.
Preheat a grill or grill pan over medium-high heat.
Brush the chicken breasts with olive oil and season with salt.
Grill the chicken for 6–8 minutes per side, or until the internal temperature reaches 165°F (74°C).
Transfer the chicken to a plate and allow it to rest for 5 minutes before slicing.
In a large serving bowl, combine the mixed greens, sliced mango, bell pepper, red onion, and half of the chopped herbs.
Drizzle most of the mango vinaigrette over the salad and gently toss to coat.
Arrange the sliced grilled chicken over the salad.
Top with avocado, the remaining herbs, and chopped peanuts.
Drizzle with the reserved vinaigrette and serve the Mango Chicken Salad immediately.