Mix diced tomatoes with green chile peppers, 1 chopped onion, salsa seasoning mix, salt, and pepper together in a bowl; refrigerate until the salsa flavors blend, at least 1 hour.
Bring a pot of water to a boil. Cook pork steaks in the boiling water until cooked through, 10 to 15 minutes. Remove pork steaks from water and cut into pieces.
Heat butter in a skillet over medium heat; cook and stir pork and remaining 1 chopped onion in the hot butter until onion is tender, about 30 minutes. Mix refried beans, burrito seasoning, and 1/2 of the salsa into the pork mixture.
Preheat oven to 350 degrees F (175 degrees C).
Spoon pork mixture down the center of each tortilla and roll tortilla around the filling. Place burritos in a baking dish. Top burritos with chili and Cheddar cheese.
Bake in the preheated oven until cheese is melted, 10 to 15 minutes. Serve burritos with remaining salsa.