Season Mackerel steaks with salt / maggi and place into saucepan.
Toast njangsang seeds, white pepper, pebbe in a fry pan for about 3 minutes. Add into a blender together with 1/2 of the onion, tomato, parsley, ginger , garlic, onion and habanero pepper. Blend with 1 cup of water until smooth.
Pour spice blend over fish. Add a pinch or two of salt. Rinse blender cup with 1/4 cup of water and pour into sauce pot.
Cover and bring to a gentle simmer and cook for 15 to 20 minutes or until fish can be easily flaked off the bone. Carefully shake or move fish around a few times while cooking to prevent the sauce from sticking to the bottom of the pot. Season sauce to taste if necessary
Then, heat about 1/4 cup of avocado oil (or canola oil /vegetable oil) and fry sliced onion until slightly brown. Pour entire content into sauce pot with fish and simmer for another 3 to 5 minutes and you're done.
Serve with boiled ripe plantains, cocoyams, cassava or rice.