Combine the peanuts, oil, shallots, garlic, lemongrass, and chile in a food processor and process to a smooth paste. Transfer to a small saucepan and place over low heat. Add the coconut milk, lime juice, soy sauce, and fish sauce and stir until smooth. Cook until the sauce is warmed through, about 2 minutes.
Taste and add more soy sauce, fish sauce, or lime ju