1. Preheat oven to 425°.
2. Combine rosemary, fennel seeds, 1/2 teaspoon salt, and 1/2 teaspoon black pepper in a small bowl. Rub spice mixture evenly over pork.
3. Heat a large skillet over medium-high heat. Add oil; swirl to coat. Add pork; cook 9 minutes, browning on all sides. Remove pork from pan. Add onion and garlic; sauté 2 minutes. Add tomato and sage; cook 1 minute, scraping pan to loosen browned bits. Add remaining 1/4 teaspoon salt, remaining 1/4 teaspoon black pepper, chicken stock, red pepper, and cannellini beans, and bring to a boil. Return pork to pan, and place pan in oven. Bake at 425° for 12 minutes or until a thermometer registers 140°.
4. Place pork on a cutting board; let stand 5 minutes. Heat pan over medium heat; cook bean mixture 2 minutes or until slightly thickened. Sprinkle with parsley. Thinly slice pork; serve with bean mixture.