In a mini blender add 1 bunch of chopped spring onions (salad onions, scallions) keep a few pieces for garnishing, 3 tablespoons of mayonnaise and 3 tablespoons of plain greek yogurt, Squeeze juice of half a lemon and blitz until spring onion is very finely chopped. Add a little freshly ground black pepper. Transfer to a little bowl and garnish with a few pieces of chopped spring onion.
Just tried another version by frying the spring onions in a little olive oil first and that was loved by both boys. I thought it was delicious too, not as strong as with the uncooked spring onions.
Cook the asparagus in a little boiling water for 5 minutes. Serve with the spring onion dip.