Heat 2 teaspoons of the oil in a large, heavy-based frying pan over high heat.
Add onion, mushrooms and garlic and saute for 5 minutes, or until soft.
Transfer to a large, ovenproof dish.
Toss meat in flour.
Heat remaining oil in frying pan and cook beef, in 2 batches, until well-browned. (Don't worry, the beef will catch on the bottom, just add a bit more oil. It will all come off when the stock and wine is added).
Transfer to onion and mushroom mixture.
Add tomato, wine, stock and capsicum to frying pan and bring to a gentle boil, scraping up any bits of beef stuck to the bottom of the pan.
Add to casserole dish.
Cover and transfer to oven to 1 1/2-3 hours. Remove lid and cook for a further 30 minutes, or until meat is tender.