For the chicken

1.  Make marinade. In a blender, purée the cilantro, scallions, garlic, jalapeño, shallot, fish sauce and brown sugar until smooth.
2. Marinate chicken.Put the chicken in a large resealable plastic bag and pour in the marinade. Seal and refrigerate for at least 2 hours or up to 6 hours. Bring to room temperature 30 minutes before cooking.
3. Prep oven. Preheat the oven to 400 degrees F and line 
a large rimmed baking sheet with aluminum foil.
4. Brown chicken. In 
a large skillet, melt 1 tablespoon of the butter in 1 tablespoon of the oil. Add half of the chicken, skin side down, and 
cook over moderately high heat until the 
skin is brown, about 3 minutes. Reduce the heat to moderate if 
the chicken starts to brown too quickly. Transfer the chicken to the prepared baking sheet skin side up and repeat with the remaining butter, oil and chicken.
5. Roast chicken. Roast the chicken in oven until it is golden brown and cooked through, about 25 minutes. Let rest for 5 minutes.

For the salad

1. Make dressing. While the chicken is roasting, make the salad. In a small bowl, whisk together 
the brown sugar, lime juice, fish sauce, and chili-garlic sauce until the sugar is dissolved. Set aside.
2. Toss salad. In a large bowl, toss together the mango, carrot and tomatoes. Drizzle 3-4 tablespoons of the dressing over the salad and toss to coat. Taste and add additional dressing to taste. You may not use all the dressing.
3. Serve. Transfer the salad to a large platter or plates and top with the roast
ed chicken thighs. Garnish with chopped 
cilantro, sliced scallions and peanuts; serve immediately.