In a medium bowl, whisk together 1⁄4 cup paprika, 2 tbsp. salt, chilli powder and sugar. Put steaks on a parchment-lined baking sheet; rub with the chile mixture. Refrigerate steaks overnight.
When you are ready to cook, remove steaks from fridge and allow to come to room temperature.
Start to make onion rings: Pour oil into a large saucepan and heat over medium-high heat (or use a deep fryer) until 180C.
Put onions and milk into a bowl; let soak for 20 minutes. In a large bowl, whisk together remaining paprika and salt, flour, chilli powder, cayenne, cumin, and pepper.
Working in batches, remove onions from the milk, shake off excess, and toss in seasoned flour. Fry onions until crisp, about 3 minutes. Drain on paper towels; season with salt. Set aside.
Heat a pan (or BBQ) over medium-high heat. Grill steaks, turning once, until medium rare, about 12 minutes. Remove and rest from around half the cooking time. Serve with onion rings.