Arrange oven racks in the upper and lower thirds and preheat to 400 degrees. Thoroughly rinse produce and pat dry. Crush fennel seeds with the bottom of a heavy pan. Reserve half of thyme sprigs for garnish and pull leaves from other half. Halve Brussels sprouts. Mince garlic. Thinly slice onion. Stem, core and slice red and yellow bell peppers into strips (julienne).

Line two baking trays with foil and coat lightly with cooking spray or use two non-stick baking trays. Arrange Brussels sprouts in a single layer, drizzle with olive oil, and toss to coat. Season with a pinch salt and pepper. Bake on upper rack for 15 minutes, or until browned on the outside and tender inside. In a separate small bowl, combine thyme leaves, fennel seeds, 1 tsp. of salt, and a pinch of pepper.

Preheat a medium pan over medium heat and add 1 tsp. of olive oil. Set aside 1 tsp. of fennel-thyme mixture and season the tenderloin liberally with remaining seasoning. Brown tenderloin on all sides, about 1 minute each side. Transfer to a baking sheet and place in oven on lower rack. Cook for 16-18 minutes or until internal temperature reaches 140 degrees. Let rest on a cutting board and tent with foil.

Heat 1 tsp. of olive oil in a medium pan over medium-high heat. Add sliced onion. Cook for 2-3 minutes until just beginning to soften, and add bell peppers, garlic, and reserved 1 tsp. fennel-thyme mixture. Cook 3-4 minutes and add vinegar and tomato sauce. When mixture begins to simmer, reduce heat to low and continue cooking 8 more minutes until all the vegetable are softened and sauce begins to thicken.

Slice the pork tenderloin into ½" slices.

Divide the roasted Brussels sprouts in the center of the plate and shingle the pork tenderloin slices in front. Spoon the peperonata generously on top of the pork and garnish with reserved thyme sprigs.