In a blender, purée the ginger, coriander seeds, turmeric, garlic, cayenne, scallions, lime zest, lime juice, soy sauce, vinegar, coconut milk, the 1/4 cup peanuts, chopped cilantro, and salt until smooth. Pour the marinade over the chicken thighs and mix well. Marinate for 1 to 2 hours in the refrigerator.
Arrange the oven racks in the middle and top of the oven and heat the oven to 450°F. Line a wide, shallow pan, a jellyroll pan, or a rimmed baking sheet with foil. Arrange the chicken thighs, skin side up, in a single layer with space between. Bake the chicken in the middle of the oven for 15 minutes for small thighs, 20 minutes for larger thighs.
Turn on the broiler. Broil the thighs 5 to 6 inches from the heat source until the chicken is golden brown on the outside and firm to the touch, 10 to 15 minutes. Be sure they don’t burn.
Arrange the chicken thighs on a platter and serve immediately, garnished with the chopped peanuts, cilantro sprigs, and lime wedges.