Trim, wash and finely slice the leeks. Place in a large saucepan with 2 tablespoons of olive oil, and cook on a low heat for 15 minutes, or until soft and sweet.Scrub and chop the new potatoes into quarters, then add to the pan. Dissolve the stock cube into 1 litre of boiling water, pour over the leeks and potatoes, and add the Parmesan rind. Bring to the boil, cover and simmer for 20 minutes, until the potatoes are tender.Trim the asparagus, then roughly chop the stems, leaving the tips intact. Add to the pan along with the peas and cook for 3 minutes. Finely grate in half the Parmesan, the zest of half the lemon and squeeze in the juice. Season to perfection with sea salt and black pepper.Finely chop the parsley. Divide the stew between bowls, discarding the rind, then finely grate over the remaining Parmesan. Drizzle with extra virgin olive oil, scatter over the parsley, serve with lemon wedges and some crusty bread, if you like.