Ina Garten's recipe for roast loin of pork with fennel involves making a mustard sauce with garlic and herbs, coating a pork loin with the sauce and baking the pork loin along with vegetables. The recipe is available on FoodNetwork.com and yields six servings.
Preheat an oven to 425 degrees F. Use a mortar and pestle or food processor to blend together two minced cloves of garlic, 1 tablespoon of salt and 1 tablespoon of fresh thyme leaves. Mix in 1/4 cup of Dijon mustard and apply the sauce to a 3-pound trimmed and tied boneless pork loin. Allow the loin to rest at room temperature for no less than 30 minutes.
Trim the tops from three small fennel bulbs and cut them through the core into thick wedges. Toss the fennel with 8 peeled and thickly sliced carrots, 10 small quartered potatoes, 2 thickly sliced yellow onions and 4 tablespoons of olive oil. Set the vegetables in a large roasting pan and roast for 30 minutes. Set the pork loin into the pan with the vegetables and cook for another 30 to 50 minutes. The pork is ready when a thermometer inserted into the middle of the pork loin registers at 138 degrees F.
Remove the loin from the pan and cover with aluminum foil to rest for 15 minutes. Return the vegetables to the oven to continue baking. To serve, remove the strings from the pork loin, cut it into thick slices and place alongside the vegetables. Season with salt and pepper to taste.