...not a hug fan of red onion, so I left these out. It's also possible to leave out the asparagus and simply stir the potatoes thru the dressing.
3 tablespoons extra virgin olive oil
freshly ground black pepper
1kg small Jersey Bennes or 30 medium waxy salad potatoes, scrubbed
2 tablespoons creamy Dijon mustard (I used Maille Dijonnaise mustard, available in most supermarkets)
zest of 1 lemon
2 tablespoons lemon juice
2 large red onions, peeled and cut into thick chunks through the root
750g plump asparagus
Cook the potatoes in gently boiling, salted water until just tender. Drain. Combine the mustard, lemon zest and juice, 2 tablespoons of olive oil, 1/2 teaspoon salt and plenty of black pepper. Toss the potatoes in the dressing while they are still warm.Place the onions in a frying pan with the remaining tablespoon of oil and cook very gently for about 15 minutes, until they just start to wilt. Cook the asparagus in plenty of gently boiling, salted water for several minutes, ensuring the spears retain their crunch. Drain and refresh with plenty of cold water, then pat dry with paper towels. Cut asparagus into chunks and mix gently with the potatoes.To serve (best done while everything is warm, but not necessarily hot), place potatoes and asparagus in a large serving bowl and the red onions on top.