Obtain fresh fish from your local store. Ensure that it is properly cleaned and de-scaled.
Fill a large deep pan 1/4 with a liquid oil of your choosing. Once the oil gets hot, place the fish gently and deep fry on medium heat for 8 minutes on each side.
Take out the fish once done, place on a rack to cool. Cut the fish into smaller chunks, if desired.
Add diced onions and chopped garlic to a medium pot with oil. Cook and stir until the mixture browns.
Add tomatoes, herbs (optional), salt and seasoning cubes to the mixture. Stir and sweat the mixture until the tomatoes have mostly broken down. Add 1 cup of water and bring the pot to a boil.
Add tilapia to the boiling mixture, then lower the heat and simmer for 15 minutes.
Serve hot with rice or ugali, and greens.