Wash and peel the potatoes, cook in boiling salted water for about 20 minutes. In the meantime, cut the lamb diagonally into slices. Peel and halve the shallots. Fry meat in hot oil, add shallots, fry briefly. Deglaze with stock and milk, simmer for 2 minutes. Wash sugar snap peas, blanch in boiling salted water. Whisk egg yolk with cream.
Flavour sauce with lemon juice, lemon peel, salt, pepper and sugar. Mix the sauce with the whisked egg yolk. Drain sugar snap peas and potatoes. Melt butter and toss potatoes. Arrange everything on plates. Wash, chop and sprinkle parsley and chives. Cut lemon into slices, garnish plates with it