Preheat the oven to 180'C.
To prepare: thinly slice the spring onions. Zest the lemon. If the asparagus are very thick, peel the bottom 3 centimetres. Break off the tough end of the stem.
For the pancetta: lie the pancetta slices on a lined baking sheet and bake in the oven until crisp. Once cool, break into small pieces.
For the potatoes: boil the potatoes in lightly salted water until tender. Whilst the potatoes are cooking, lightly wilt the sliced spring onion in a hot pan. Drain and then crush the potatoes with a fork. Mix the spring onions and pancetta into the crushed potatoes.
Cook the asparagus in a pan of lightly salted boiling water until tender.
For the poached eggs: bring a large pot of water to the boil, reduce to a simmer and add the vinegar. Crack the eggs into the pan one at a time. Cook for 4 minutes.
For the lemon butter sauce: add the lemon zest to 100ml of water in a saucepan. Bring to the boil, reduce by half and then lower the heat. Whisk in the butter a little at a time until emulsified. Season with salt and pepper and then add a squeeze of lemon juice.
Plate the potatoes and lay the asparagus on top. Add a poached egg and drizzle with the lemon butter sauce to finish.
«Leave out the potatoes to serve this seasonal dish as a starter.»