Combine the onion, garlic, jalapeno, soy sauce, sugar, thyme, cinnamon, allspice and a pinch of salt together in a food processor and blend for a couple of minutes, scraping up pieces that cling to the walls to make sure everything is blended evenly.
Combine the jerk rub and the chicken legs in a casserole dish that is just big enough to fit the chicken pieces. Work the rub into the chicken, making sure to put the mixture under the skin as well. Cover and let the chicken marinate in the refrigerator for at least 3 hours or up to overnight.
Preheat the oven to 400 degrees F.
Drizzle the marinated chicken with vegetable oil and season with salt. Roast it in the marinade in the center rack of the oven until an instant-read thermometer shows an internal temperature of 165 degrees, about 40 minutes. Let the chicken cool slightly, then pull off the meat in large shreds, discarding the bones. Toss the shredded chicken with any leftover juices in the pan.
Sandwich build: Spread some Pickapeppa Sour Cream on both sides of the bread. Place some of the Mango Chutney on the bread. Put on a layer of shredded chicken and top with some Fried Plaintains and cilantro. Serve extra plantains on the side. Enjoy, man!
Mix together the sour cream, pickapeppa sauce and lime zest in a small bowl. Season with salt and pepper.
Mix together the mangos, sugar, raisins, ginger, garlic, jalapeno and salt to taste in a medium bowl. Cover and refrigerate for at least 30 minutes or up to overnight.
Combine the mango mixture with the vinegar and turmeric in a small saucepan and bring to a simmer. Cook, stirring occasionally to prevent the chutney from sticking to the pan until thickened and thoroughly combined, about 20 minutes.
Fill a Dutch oven halfway with canola oil and heat to 350 degrees F.
Peel the plantain and slice it lengthwise into long thin strips. (A mandolin slicer will give you the best results.) You can crack the peppercorns by crushing them with a heavy pan on a cutting board; you are looking for a very coarse grind. Drop the plantain strips in the hot oil and allow them to fry up crispy, about 1 minute. Transfer the plantains directly to a paper towel-lined plate and immediately season with salt and the cracked black peppercorns.
Pickapeppa sauce, also called Jamaican ketchup, is a condiment made with tomatoes, onions, cane vinegar, mangoes, raisins, peppers and other spices. It is aged in oak barrels and has a sweet and mellow flavor. It is available online and in specialty stores.