Clean the vegetables and remove the seeds from peppers then slice into long strips. Cut the onions and garlic in half and slice thinly.
Ensure that the parsley is clean and dry. Chop and set aside for later.
Drizzle olive oil in a large pot and place on a medium heat. Add the onions and bay leaf and cook slowly until soft. Add the peppers and stir cook for 3 minutes.
Season the fish with salt. Set aside.
Crack black pepper and add a pinch of sea salt to the pot. Add the white wine and bring to a boil. Once boiling, turn off the heat and set aside.
Remove the skin from the orange, slice in half and add half to the mix and stir.
Heat a dry pan over medium heat and add the mustard seeds and cloves. Stir for 3 minutes to release the aromatics and then add the onion mix. Stir and turn off the heat.
If you have a grill, cook the fish over very hot coals for 45 seconds on each side. Once cooked add a squeeze of lemon and a crack of black pepper.
Scatter tuna over a serving tray, pour over the onion mix and serve with rice or salad on the side.