1. Put a large pan of water on to boil. Scrub the potatoes and slice them into ½cm-thick rounds. Add them to the pan of boiling water. Bring back to the boil, then simmer for 2 mins.
2. While the potatoes simmer, pop the steaks onto a plate. Pierce them all over with a fork to help them tenderise. Use a mortar and pestle or a small bowl and the bottom of a jar to roughly crush the peppercorns. Sprinkle them over the steaks with a pinch of salt. Set aside on a plate. Drain the potatoes. Set aside to steam dry in the colander.
3. Peel and finely slice the shallots. Peel and crush the garlic. Pick the rosemary leaves off their stems and roughly chop the leaves. Pop the salad leaves in a large bowl. Whisk 1 tbsp red wine vinegar with 1 tbsp olive oil and a pinch of salt and pepper to make a dressing. Taste, add more salt and pepper if you think it needs it, then add to the salad leaves. Toss to coat. Set aside.
4. Fill the pan you cooked the potatoes in with water, pop on a lid and bring to the boil. While the water is heating up, put a wok or deep frying pan over a medium heat. Add 1 tbsp oil and the potatoes. Fry for 12-15 mins, turning now and then, till golden brown.
5. Put a separate frying pan on a high heat for 3 mins. Add half the butter and the steaks. Fry for 1 min on each side (or a little longer if you prefer your steaks well done). Transfer them to warm plate or board and loosely cover with foil. Set aside to rest for 5 mins.
6. While the potatoes fry, put the steak frying pan back on the heat, but keep it low. Add the shallots, season and fry for 5 mins till starting to soften. Stir now and then.
7. The water in the pan should be boiling by now. Add the sugar snap peas (keep them whole, you can eat the pod) and simmer for 3 mins till the pods are tender. Drain and return to the pan. Add the remaining butter. Pop on a lid and let the peas sit for a few mins to soak up the melting butter.
8. Stir the garlic into the shallots. Pour in the cream. Gently simmer for 2 mins till the cream is warmed through. Taste the sauce and add more salt and pepper if you think it needs it.
9. The potatoes should be browned by now. Add the rosemary and toss to coat the potatoes. Pile the potatoes up on warm plates. Add the steaks and spoon over the cream sauce. Serve with the sugar snap peas and salad leaves.