Remove stems and seeds from the dried chiles. Quarter the tomatoes and chop the onion.
Sauté tomatoes, onion, chiles, and garlic in a little oil until softened.
Blend the sautéed mixture with cumin, paprika or achiote, brown sugar, and enough liquid to make a smooth sauce.
Place the chicken in a baking dish, drizzle with oil, and coat thoroughly with the adobo sauce.
Marinate for at least 3 hours (or overnight).
Add baby potatoes and bay leaves around the chicken. Cover tightly with foil.
Bake at 375°F for 1 hour. Remove foil, baste with pan juices, and bake uncovered 30 more minutes until golden.
Rest briefly, carve, and serve with the potatoes and extra sauce.