Heat a large skillet over medium-high heat. Add ground beef, add onions, garlic, and mushrooms; saute until onion is golden brown. Season with salt and black pepper.
Stir 2 cups hot water, bouillon cubes, and tomato paste into meat mixture. Stir together 1 1/2 cups cold water and flour; stir into pan. Reduce heat to low, and simmer for 1 hour.
