1. In a small bowl combine mayo, ketchup, black pepper, ground cayenne pepper, garlic and lime juice.
2. Place 50g flour aside on a shallow plate. In medium bowl combine 150g flour, cayenne pepper, cumin, black pepper, garlic powder, beaten egg and enough beer to reach the desired batter consistency.
3. Heat oil in deep fat fryer to 180°C.
4. Dip onion rings in flour on shallow plate and then into batter. Fry battered onion rings in the hot oil until browned, about 4 minutes. Place on paper towels to help drain off any excess oil.
5. Serve hot with garlic lime mayo and a craft beer.