Mix 1 tbsp smoked paprika with 1 tsp ground cumin and a good pinch of salt and pepper. Dust over the pork. Use a fork to pierce the meat all over - this tenderises the meat and helps get more flavour into it. Set aside.
Drain your butter beans. Pop in a sauce pan. Peel the garlic cloves. Add them, a good pinch of pepper, and 1 tsp ground cumin. Simmer for 10 mins.
Strip the leaves from 1 rosemary stalk. Finely chop. Add to the butter beans, along with the zest and a good squeeze of juice from your lemon. Puree the butter beans till smooth, adding a little more lemon juice or water, if needed, to get a nice smooth, houmous-like texture.
Set a large frying pan over high heat. Halve, peel and thinly slice your onion. Rub 1 tsp olive oil into each pork steak, on both sides. Press the pork into the hot pan. Add the remaining rosemary sprigs and the sliced red onion. Cook the pork 3-5 mins on each side, or till nicely golden and fully cooked through - the meat will be fully white in the centre. Stir and sizzle the onions alongside the pork. Spoon them out as soon as they're tender and a little charred around the edges.
Let the pork rest. Thinly slice your red pepper, discarding the seeds and stem. Mix with the watercress, plucking out any thick stems. Toss with a spritz of lemon juice, a pinch of salt, and 1 tsp olilve oil.
Thinly slice the pork, perch it and the sizzled onion atop of bed of butter bean mash. Serve the salad on the side.