• Spring onions look much like giant scallions, but with a rather more bulbous base. It's that base that you want to use for this recipe.
• Wash and dry your spring onions well. Trim off the root ends, then cut off the green tops. Depending on their size, cut the bulbs lengthwise in halves or quarters. If they're very small, you may want to leave them whole.
• Heat melt a dab of butter in some olive oil in a sauté pan or braiser. When the butter is just melted, add the spring onions (and the pancetta, if using) and let them sauté very gently for a few minutes, seasoning with salt and pepper as you go.

If using frozen peas:

• Add a ladleful of broth or water and cover. Let the onions simmer until they are almost tender. If your onions are young and fresh, this should take no more than 5 minutes. Uncover the pan and add the peas, mixing gingerly. Continue simmering, uncovered, until the onions and peas are done and the liquid in the pan has almost, but not quite, evaporated. A minute or two should be enough. Taste and adjust for seasoning before serving.

If using fresh, shelled peas:

• Add the peas to the onions, give them a turn, then add a ladleful of water or broth. Cover and simmer gently until both peas and onions are tender, about 10 minutes or so if your peas are young. If there is excess liquid left in the pan, uncover, raise the heat and let the liquid reduce. Taste and adjust for seasoning before serving.