Heat oil in a large dutch oven pot over medium-high heat. Season beef with salt and pepper and add to the pot. Cook for 2-3 minutes on each side until golden brown. Remove and set aside.
Add onions and garlic and sauté for 1-2 minutes until soft and translucent. Add peppers and cook for an additional minute. Add mushrooms and cook until golden, about 2 minutes, gently stir to avoid sticking.
Stir in Harissa paste and add diced tomatoes. Reduce heat to simmer.
Cover pot and simmer for 20 minutes. Add beans and cover and let simmer for an additional 15-20 minutes until beef is tender and pulls apart.
Serve with chilli peppers and crust bread for dipping.