Pile the flour into a large bowl with a small pinch of sea salt. Mix in 150ml of water, knead lightly on a flour-dusted surface for 2 minutes, then cover and leave to rest. Trim the pork of any sinew, then cut into two chunky pieces and rub all over with black pepper. Place in a 30cm non-stick frying pan on a medium-high heat with 1 tablespoon of olive oil and cook for 15 minutes, or until just cooked through, turning regularly. Use a fork to scrape down the outside of the cucumber, then finely slice. Trim the spring onions, then finely slice with the radishes. Wash the lettuce and click apart into cups. Crush the wasabi peas in a pestle and mortar.
Move the pork to a plate, leaving the pan on the heat. Evenly spoon the hoisin sauce over the pork and leave to rest. Pour ½cm of water into the hot pan. Lightly rub a large sheet of greaseproof paper with oil, sit the dough on top, gently pull and stretch it out to 30cm, then lightly score into quarters. Trim the paper so you can sit both paper and dough inside the pan, place inside, cover, and steam for 5 minutes, or until cooked through. Serve everything at the table.