Heat 1 teaspoon of olive oil in a large non-stick skillet (12-inch / 30cm) over medium-high heat. Add the diced onion (use the full onion — half is for the burrito, half for the ragu) and cook for 3-4 minutes until softened. Add all 750g of ground beef, break it up, then let it sit undisturbed for 1-2 minutes to brown properly. Stir and repeat until no pink remains and the beef is well browned, about 8-10 minutes total. Meanwhile, in a separate medium saucepan, heat 1 teaspoon of olive oil over medium heat. Add the diced carrot and celery and cook for 5 minutes until slightly softened.

Transfer approximately one-third of the browned beef mixture (about 250g) into the saucepan with the carrots and celery. Add the tin of chopped tomatoes and 1 teaspoon smoked paprika. Stir to combine, reduce heat to low, and simmer for 30 minutes, stirring occasionally, until the sauce has thickened and the flavours have melded.

To the remaining beef in the large skillet, add the minced garlic and cook for 30 seconds until fragrant. Add the passata and 3 tablespoons of water, stir to combine, and cook for 1-2 minutes until the liquid is mostly absorbed.

Add the oregano, cumin, onion powder, salt, paprika, and black pepper to the beef. Stir well to coat evenly and cook for 1-2 minutes until fragrant. Add the drained black beans and stir through until heated, about 2 minutes. Ensure the beef filling has reached an internal temperature of 160°F / 71°C before serving.

Warm the flour tortillas in a dry skillet for 20-30 seconds per side, or wrap in a damp paper towel and microwave for 30 seconds. To assemble, spoon the spiced beef and bean mixture down the centre of each tortilla. Top with grated cheese, halved cherry tomatoes, and mashed avocado with lime juice. Fold in the sides and roll tightly into a burrito.