Step 1

Toast cumin seeds and coriander seeds in a dry small skillet, preferably cast iron, over medium heat, tossing occasionally, until very fragrant and just beginning to darken, about 5 minutes. Transfer to a plate; let cool. Reserve skillet.

Step 2

Finely grind seeds in spice mill or with mortar and pestle. Transfer ground cumin and coriander to a blender and add tomatoes, garlic, orange zest, ½ cup orange juice, ½ cup peanuts, and 1 cup water. Purée until sauce is smooth.

Step 3

Arrange 6 lime halves, cut side down, in reserved skillet and cook, undisturbed, over medium-high heat until charred, 5–8 minutes. Transfer to a large plate.

Step 4

Heat oil in a large Dutch oven over medium-high. Working in 2 batches, cook chicken, skin side down, until golden brown and crisp, 6–8 minutes per batch. Transfer to a plate. Add onion and cook, stirring often, until softened and browned, about 5 minutes. Return chicken to pot and pour sauce over. Bring sauce to a simmer. Season with salt and pepper; cover, leaving lid slightly askew. Cook, stirring in 2 charred lime halves halfway through (reserve remaining charred limes for serving), until chicken is very tender, about 1 hour.

Step 5

Transfer chicken to a platter, leaving sauce behind. Squeeze juice from uncharred lime into sauce. Add remaining ½ cup orange juice and season with more salt and pepper if needed. Spoon sauce over chicken. Top with herbs and more peanuts; drizzle with chili oil. Serve with reserved charred limes.