In a large zip bag add the fish seasoning, onion granules, garlic granules, soy(a) sauce, homemade browning sauce, chadon beni, chilli powder, black pepper, salt pink and water.
Add the tuna steaks and then secure the bag.
Gently shake the bag so the tuna steaks are completely marinated.
Refrigerate for up to 2 hours.
After the given time preheat a medium sized frying pan or skillet with 2 tablespoon of olive oil on medium heat.
Remove the tuna steaks from the bag (reserve the marinade) and sear the steaks to your preference. I sear mine for 3-4 minutes per side.
Once the tuna steaks are seared, remove them from the pan and set aside.
Add another 2 tablespoon of olive oil to the frying pan on medium heat.
Saute the onion and garlic until soft and translucent.
Pour in the reserved marinade then stir in the tomato paste and add the sprigs of thyme (add a few tablespoons of water if the sauce is too thick).
Add the tuna steak to the pan, put the lid on and simmer for 5 minutes.
Do a taste test and add any further seasoning if required before serving.