3-lb. boneless pork loin (have your butcher leave 1/8 inch fat on the top)
1-1/2 lb. small yellow potatoes (about 10), halved
3 medium parsnips, peeled, cut lengthwise into quarters, and cored
2 medium sweet onions, halved lengthwise and cut into 1/4-inch slices
1 large fennel bulb, stalks trimmed, bulb quartered, cored, and cut lengthwise into 1/4-inch slices (fronds reserved)
1-1/2 cups lower-salt chicken broth
3/4 cup dry white wine
In a small bowl, combine 1 Tbs. of the oil with the garlic, rosemary, fennel seeds, coriander, 1-1/2 Tbs. salt, and 3/4 tsp. pepper to make a paste; set aside.
Pat the roast dry with paper towels. Rub the paste over the entire roast. Cover and refrigerate at least 4 hours or overnight.
Position a rack in the center of the oven and heat the oven to 400°F.
Remove the roast from the refrigerator and let sit at room temperature for 30 minutes.
Reduce the oven temperature to 350°F. Put the roast, fat side up, on top of the vegetables. Add the chicken broth and wine, and roast, basting the meat and vegetables occasionally, until an instant-read thermometer inserted into the roast registers 130 F, about 45 minutes to 1 hour..
Toss the potatoes, parsnips, onions, and fennel in a bowl and season with 1 Tbs. tsp. salt and 1/8 tsp. pepper and add the remaining 1/4 cup olive oil. Spread evenly on roasting pan and put in oven, turning occasionally, until a fork inserted in the center of each type of vegetable meets little resistance, about 40 minutes.
Transfer the roast to a serving platter or carving board, cover loosely with foil, and let rest for about 20. Transfer the vegetables to a large, oven safe platter and keep warm in the turned-off oven.
Pour the juice from the roasting pan into into a 1-quart saucepan, leaving the fat behind, and put over medium-high heat. Add the remaining and simmer until the jus is slightly reduced, 3 to 5 minutes. Strain through a fine sieve and season to taste with salt and pepper.
Arrange the pork on a platter with the vegetables, garnish with the fennel fronds, and serve with the jus on the side.