In a medium bowl, mix together the ground beef, eggs, bread crumbs, onion, garlic, Worcestershire sauce, green pepper and Cheddar cheese until well blended. Form into walnut-sized balls.
Melt butter in a large skillet over medium-high heat. Add meatballs, and brown evenly. Remove from the skillet, and set aside. Stir flour and instant coffee into the pan drippings. Add beef bouillon and water to the pan, and mix well. Bring to a boil, and allow to thicken. Stir in sour cream.
Return meatballs to the skillet, and let them simmer in the sauce for 20 to 40 minutes. Serve as an appetizer, or over rice or egg noodles as a main course.