4 garlic cloves, crushed 1 tablespoon fennel seeds 1/2 teaspoon salt, plus more to taste 1/2 teaspoon freshly ground black pepper, plus more to taste 1 tablespoon olive oil Two 3/4 pound pork tenderloins, trimmed of fat and membrane 1 small onion, chopped 2 Granny Smith apples, peeled, cored and sliced about 1/4" thick 1/2 cup dry white wine
Preheat oven to 425ºF.
Using the flat side of a large knife, mash together garlic, fennel seeds and 1/2 teaspoon salt together on a cutting board. Place in a small bowl and stir in pepper and 1/2 teaspoon of oil.
Rub fennel-seed mixture evenly over tenderloins, pressing it into crevices. Fold the thin tails underneath and secure with butcher’s string or a toothpick.
Heat a large oven-proof skillet over medium-high heat. Add tenderloins and cook until lightly browned on both sides, about 1-1/2 minutes per side. Remove tenderloins to a plate. Add apple slices and onions to the skillet and saute over medium heat for about 5 minutes. Spread mixture evenly over bottom of skillet and sprinkle with salt and pepper. Place tenderloins ontop of apple mixture and transfer skillet to oven and roast for about 20 minutes, or until internal temperature registers 150ºF. Transfer pork to a plate and tent with foil.
Pour wine in the skillet over the apple mixture. Toss and stir over high heat until slightly reduced, about 2 minutes. To serve, cut pork into diagonal slices and serve with apple/onion mixture.
When pork is ready, transfer it to a carving board, cover loosely and keep warm.
Place skillet (do not wipe it) over medium-high heat. Pour in wine and stirring, bring to a boil. Boil until reduced by half, about 2 minutes. Add to fennel sauce, along with sour cream, if using. Taste and adjust seasonings.
Remove string or toothpicks from tenderloins and carve into 1/2" thick slices. Spoon the sauce onto plates and fan pork slices over top. Garnish with a few fennel fronds.