Heat the oil in a small frying pan over medium-high heat. Sauté the onion for approximately 5 minutes, or until opaque. Toss in the prawns and cook for a further 1 minute, stirring and turning them over to cook evenly.
Add the pepper, cumin and salt and stir for a minute further. Add the peanut butter and stir to incorporate. Turn off the heat, stir through the chopped coriander and set aside to cool, or you can even keep it in the fridge until needed.
Cut the skin off the plantains and discard it. Chop 1½ of the explanations into 1 inch chunks and put them into a small saucepan. Cover with water, put on the stove and bring to the boil. Boil for 8-10 minutes or until cooked through. Drain well, put the cooked plantain back into the saucepan and mash it well while still hot.
With the remaining uncooked plantain, grate it finely straight into the mashed, cooked plantain.
Wipe out the saucepan, or use a small frying pan, and heat the 2 tablespoons of olive oil over medium high heat. Sauté the onion for approximately 5 minutes, or until opaque. Stir through the achiote paste, if using, followed by the cumin, peanut butter and seasoning. Turn off heat and allow to cool.
When the plantain mixture and onion-peanut mixture are cool enough to handle, mix them all together in a large bowl. Using your hand is best as you need to squish it all together really well.
Divide the plantain mixture into 6 oval balls.
Divide the prawn filling mixture into 6 even portions.
To make the corviche, roll the ball of plantain using wet hands. Flatten it to about an 11cm x 8cm oval, lay the prawn filling down the centre, then bring the sides over to encase the filling. Seal it closed and form it into an oval ball again.
Repeat with the remaining plantain and filling, making sure your hands are wet as it isn’t as sticky.
To cook, heat the canola oil in a large saucepan. You want the temperature to be around the 180°C mark. Deep fry the corviche a few at a time, just don’t overcrowd them. Cook in the oil for about 5 minutes until nice and golden and cooked through. Drain on kitchen towels and serve hot or at room temperature.
Put the tomatoes, garlic and sliced onion into a small saucepan and top with water. Bring to the boil and cook for 2 minutes. Turn off the heat, reserve ½ cup of the boiling water and drain the rest and set aside to cool bit.
Blacken the red chillies over a flame or under a grill. Peel off the skins and discard the stems.
Peel the tomatoes and discard the sin. Toss the peeled tomatoes, boiled garlic and charred chillies into a blender, or use a stick blender to purée roughly.
Pour the purée into a small bowl, add the boiled onion, vinegar and salt and pepper. Store in the fridge until needed.
Combine all ingredients in a small bowl and mix together. Give it a mix after 15 minutes, or so, to keep it pickling. The onion will soften over time. Keep refrigerated until needed.