- 4 burger buns
- 650g fresh tuna, minced
- mixed spices, to taste (turmeric, cumin, anise)
- 200g mozzarella
- 8 lettuce leaves
- 300g tomato passata (pureed tomatoes)
- 1 tsp mustard
- 2 tbsp brown sugar
- 200 ml white vinegar
- 2 tsp soy sauce
- 2 red onions
- 1 bay leaf
For the ketchup
Cook the tomato passata in a saucepan with 100 ml vinegar, 1 tablespoon of brown sugar, soy sauce and a pinch of salt for 10 minutes over low heat.
Slice the onions thinly and caramelise in a frying pan with 1 tablespoon of brown sugar, 100 ml of vinegar, two pinches of salt, and the bay leaf for 15 minutes on low heat.
For the tuna burger
Add the spices to the minced tuna. Mix well and then form into 4 burgers; grill for 3 minutes.
In the meantime, blend the mozzarella into a cream.
To assemble, spread the mozzarella cream and homemade ketchup on the sliced burger buns, top with a leaf of lettuce, the tuna burgers, then the onions and mustard, and finish with more ketchup and another leaf of lettuce.