Preheat an oven to 350 degrees F (175 degrees C). Grease a 9x5 inch loaf pan.
Lightly mix the ground chuck, onion, brown sugar, egg, salsa, and bread crumbs in a bowl, and spoon into the prepared baking dish.
Bake in the preheated oven for about 45 minutes, until the meatloaf is cooked all the way through and the top is browned. An instant-read thermometer inserted into the center should read at least 160 degrees F (70 degrees C).