In a large frypan over medium-high heat,saute the beef mince for 5 minutes. Add the onion and red capsicum; saute for 5 more minutes, or until onion is tender. Drain the fat.
Mix in tomato paste and water, stirring until paste is dissolved. Stir in garlic, chilli powder, paprika, cumin, vinegar, brown sugar, oregano, salt and pepper. Continue to heat for 5 to 10 minutes or until mixture is thick and stewy. Serve over hamburger buns.