In a large skillet, over medium-high heat, cook/crumble the ground beef with the onions until browned and cooked through.
Add minced garlic and bell peppers; cook for 1 - 2 minutes; remove from heat and drain grease.
Place back on the heat; season lightly with salt, pepper, ketchup, yellow mustard and tomato paste; stir to combine.
Sprinkle flour over the meat mixture; stir to combine; cook for 2 minutes or until the smell flour of is no longer present.
Add the beef broth mixture, in small splashes, and use a silicone spatula to clean the bottom of the pot; this will add more flavor to the sauce; don’t add the liquid too quickly in order to keep the base nice and thick; bring to a boil; reduce to a simmer; let it thicken and reduce for 5 minutes; remove from heat.