In a small bowl combine marmalade, garlic, coriander, cumin, soy sauce, rice wine vinegar, peanut butter, lime juice, orange juice, crushed red pepper and black pepper. Whisk the ingredients together until evenly incorporated.
Season the pork tenderloin with salt and pepper and place it in gallon sized zip-locking plastic bag. Carefully, add in the marinade, and then gently squeeze the excess air out of the bag before sealing it shut.
Refrigerate and let the meat marinade for at least 30 minutes, or for as long as 8 hours.
Heat the vegetable oil in a large oven-proof skillet (like cast iron or even a dutch oven) over medium-high heat, until the oil is shimmering.
Add the pork tenderloin, and sear on all sides, until it’s nicely browned, about 8-10 minutes total. Place the entire skillet into the preheated oven, and cook at 425 degrees for about 20 minutes, or until a meat thermometer registers 160 degrees. Remove the meat from the oven and let it rest for about 10 minutes before slicing.
While the pork is in the oven cooking, pour the marinade out of the plastic bag and into a small saucepan. Add in 1/4 to 1/2 cup of water.
Bring the mixture to a boil and simmer until slightly thickened, about 5 minutes.
Slice the tenderloin and pour the sauce over top. Sprinkle with chopped cilantro for garnish, if desired.