Make the Sauce: Add mayonnaise, garlic, cilantro, jalapeño, and lime juice to a blender or food processor. Blend until smooth and creamy. Taste and adjust spice or lime to your preference. Refrigerate until ready to serve.
Marinate the Chicken: In a bowl, whisk together olive oil, lemon juice, garlic, paprika, cayenne, oregano, thyme, onion powder, salt, and pepper. Add chicken thighs and coat thoroughly. Cover and marinate for at least 2 hours (overnight for best flavor).
Bake the Chicken: Preheat your oven to 425°F (218°C). Arrange chicken in a single layer in a baking dish. Bake for 20 minutes, flip, and cook another 5–10 minutes until internal temperature reaches 165°F (74°C).
Serve: Let chicken rest for 5 minutes. Serve with generous spoonfuls of green sauce on the side or drizzled on top.