Preheat the oven to 200°C/Gas Mark 6. Heat half the oil in a non-stick frying pan and cook the onion over a low heat for 5 minutes. If using runner beans, destring and slice into 3cm pieces. Tip the onion into a small ovenproof dish and add the beans.
Heat the remaining oil in the pan and lightly brown the pork for about 2 minutes per side. Spear all 4 steaks with a carving fork and hold the rind against the hot pan to brown. Sit them on top of the onions and beans.
Crush the fennel seeds in a pestle and mortar or with a rolling pin, and sprinkle over the pork with a bit of salt and black pepper.
Bring the stock to the boil and pour over the pork and beans. Cook in the oven for 15 minutes, until both beans and pork are cooked.
Make the gremolata by mixing the garlic, lemon zest and parsley, and spoon over the pork before serving.