Finely slice the onions. Cut the new potatoes into quarters. Snap off tough stalks and slice into short lengths the asparagus spears. Chop the little gem lettuces. Chop the mint. Chop the parsley.
- 1 Heat the butter and oil in a large pan over a medium heat, then add the onion and gently fry until beginning to caramelise.
- 2 Add the potatoes and two-thirds of the stock.
- 3 Bring to the boil, then simmer, stirring occasionally, for 15-20 mins until the potatoes are tender.
- 4 Add the asparagus, lettuce, cream and remaining stock.
- 5 Stir gently, bring to the boil, then simmer for 3-4 mins, until the asparagus is tender, and the liquid has reduced by one-third to a half.
- 6 Season, then stir through the chopped herbs and a generous squeeze of lemon juice.
- 7 Serve immediately.