Cook beef, onion, and garlic in a saucepan over high heat for 5 minutes.
Stir in spices and cook for 2 minutes.
Add tomato purée, sugar, and stock, then simmer covered for 30 minutes.
Preheat the oven to 180°C.
Scrunch a 1 metre foil sheet into a 10cm ball and place on a baking sheet.
Brush a tortilla with oil and drape it over the foil ball to form a bowl.
Bake for 5 minutes until crisp and set.
Mould the warm tortilla over an upturned tumbler to create a flat base and let cool.
Uncover the beef and cook over high heat until the liquid evaporates.
Toss lettuce, tomatoes, cucumber, and spring onions with lime juice.
Fill tortilla bowls with salad, top with hot beef, cheese, crème fraîche, and salsa.