Combine ½ cup of the onion with the black-eyed peas, kombu, and bay leaf in a stovetop or electric pressure cooker and add enough water to cover by 1 inch. Bring to high pressure and cook for 20 minutes.

Turn off heat and let the pressure release naturally. The black-eyed peas should be very soft. Open the pressure cooker and cook on medium-high, stirring frequently to prevent scorching, to reduce the liquid until it is thick and creamy, about 20 minutes.

While the black-eyed peas are cooking, combine 1 cup of the remaining onion with the bell pepper, tomato, and Scotch bonnet (using more or less depending on your appetite for heat) in a blender and puree until smooth.

Scoop the palm oil into a large skillet over medium-high heat. When it melts and starts to simmer, add the remaining ½ cup onion and sauté until tender, about 6 minutes. Stir in the cayenne, grains of selim, if used, and ½ teaspoon of the salt and cook until fragrant, about 30 seconds.

Pour in the pureed bell pepper mixture, reduce the heat to low, and cook, stirring occasionally, until the sauce reduces, darkens, and loses its raw edge, about 20 minutes.

When the black-eyed peas are ready, add them to the sauce in the skillet with a little water if needed to loosen the mixture. Stir to combine and cook until the flavors meld, 3 to 4 minutes. Taste and add more salt if needed. Remove from the heat and cover to keep warm.

To make the plantains, line a plate with paper towels. Peel the plantains by using a paring knife to slash a shallow cut down the length of each plantain, then remove the peel. Cut them in half lengthwise, then into ¾-inch half-moons or cut on the bias into ¾-inch slices. Sprinkle the plantains with the remaining ½ teaspoon salt.

Pour the oil to a depth of ½ inch into a large skillet set over medium-high heat. When it shimmers, add the plantains (working in batches, if necessary, to avoid overcrowding) and fry until browned on the bottom, 2 to 3 minutes, then use tongs to turn them over and cook until browned on the second side, 1 to 2 minutes. Transfer them to a paper-towel-lined plate.

To serve, divide the beans among shallow bowls and tuck the plantains on one side. Serve hot, with rice.