How to Make It
In a small skillet, lightly toast the coriander, cumin and fennel seeds over moderate heat until fragrant, about 2 minutes. Transfer to a plate and let cool. In a spice or coffee grinder, grind the seeds to a fine powder.
In a blender, combine the cilantro with the olive oil, onion, mint, orange juice and zest; puree until smooth. Scrape the marinade into a large glass baking dish. Stir in the ground spices. Season the pork with pepper and add to the marinade; turn to coat. Refrigerate for 2 to 4 hours, turning occasionally.
Light a grill or preheat a grill pan. Remove the pork from the marinade and scrape off any excess. Season generously with salt and pepper. Lightly brush the grate with vegetable oil. Grill the tenderloins over a medium-hot fire or in the grill pan, turning occasionally, for 20 to 25 minutes, or until an instant-read thermometer inserted in the thickest part registers 140° for medium.
Transfer the tenderloins to a cutting board and let rest for 5 minutes. Cut the meat into 1/4-inch-thick slices. Split the Cornmeal-Cheddar Biscuits, spread with Spiced Tomato Ketchup and make sandwiches with the pork.