Blend the bell peppers, scotch bonnet, and 1 onion in a blender.
Heat the oil in a pan.
Chop the remaining onions and cook in the oil until soft and translucent before adding the garlic.
Pour in the blended mixture and allow to cook about 10 mins.
Add the smoked mackerel and king prawns followed by salt.
Allow to cook for 5 mins.
Add the baby leaf spinach and allow to wilt.
Remove from heat, pour in the chopped basil and serve.
Notes
Add more salt to the sauce, if required; only after you've added the smoked mackerel. Smoked mackerel is quite salty and the salt will leach into the pot.