Fish in a spicy red sauce

Ingredients

• 4 medium slices of tuna fish, you can use fillet fish actually
• 2 large onion chopped
• 3 tbsp of tomato paste diluted in 3 tbsp of water
• 1 tsp red chili flakes
• 1/2 cup olive oil
• 1/2 cup water
• 1 1/2 tsp salt