Process the chilies, onion, and ginger into a smooth puree using a blender or food processor. Add the chile paste, peanut oil, soy sauce, allspice, garlic salt, and bay leaf and process to blend well.
Divide the marinade in half and, wearing rubber gloves, rub half the marinade over the pork. Cover the tenderloins with plastic wrap and let refrigerate overnight in the refrigerator. Reserve the remaining marinade.
When ready to cook, prepare a hot fire in your grill. Remove the pork from the marinade and pat dry with paper towels.
Place directly over the coals, cover, and cook, turning every 10 minutes, until an instant-read meat thermometer inserted into the center registers at least 145 degrees F, about 30 minutes. Cover between turns. If you like your pork more done, then aim for 155 to 165 degrees F.
Combine the reserved marinade in a small saucepan with the water and simmer gently over low heat for 10 to 15 minutes, stirring to prevent scorching or burning.
Remove the pork from the grill and let it rest for 10 minutes before slicing. Serve with the heated marinade and barbecue sauce on the side.