Preheat the oven to 180C.
Heat half the oil in a casserole dish and lightly brown the meat all over. Set aside.
Thinly slice the onion and fennel.
Add the remaining oil and sauté the onion and fennel over a low heat for 5 minutes. Pour over the stock.
Put back the pork.
Using a pestle and mortal, crush the fennel seeds, salt and black pepper. Scatter this all over the pork.
Put the dish in the oven and roast for 15 minutes. Add the beans and roast for another 5 minutes, or until the pork is cooked through. Don't overcook though!
Make the gremolata: mix the minced garlic with the lemon zest and parsley.
Scatter this over the dish, then cut the pork into medallions and serve with the beans and fennel.