Wash the fish and pat dry; then season with salt and the chili flakes. Heat olive oil or any other type of oil; then add the fish and onion. While he onion is cooking sear the fish gently on each side making sure they do not break. Once both sides of the fish is seared, add the tomatoes, thyme and habanero peppers; then cover to let it cook for about 20minutes(do not stir). After 20 minutes, season to taste with salt and bouillon; then add the palm oil and let it cook for another 5-10 minutes or until the palm oil has mixed well with the sauce. Shake to spread the seasonings; then add the basil and set aside to serve.
Notes
You could use only olive oil or palm oil if you choose to.
Recipe by Nigerian Lazy Chef at https://www.nigerianlazychef.com/2016/06/mackerel-and-tomato-sauce/