In a small skillet, cook bacon over medium heat until crisp; remove to paper towels. Drain, reserving drippings. In a small bowl, dissolve bouillon in boiling water. In a large bowl, combine the egg, 1/4 cup of bouillon, bread crumbs, 1/4 teaspoon salt and pepper. Crumble beef over mixture and mix well. Shape into 1-in. balls.
In a large skillet, brown meatballs in 1 tablespoon of reserved bacon drippings; drain. With a slotted spoon, transfer to a greased 11x7-in. baking dish. In the same skillet, saute onions until tender; drain. Place over meatballs.
In a saucepan. combine flour and 2 tablespoons or reserved drippings until smooth. Gradually stir in beer or broth and remaining bouillon. Add the brown sugar, vinegar, thyme and remaining salt. Bring to a boil; cook and stir for 2 minutes or until thickened. Stir in browning sauce if desired. Pour over meatballs. Cover and bake at 350° for 40-45 minutes or until meat is no longer pink. Sprinkle with bacon.