1. Scrub the potatoes, cutting the big ones into smaller pieces. Place them in a pot of salted boiling water. Boil, covered, over a low heat for approx. 10 min., or until tender.
2. Cut the cheese into thin slices, then break the slices into smaller pieces.
3. Place the asparagus pieces in a bowl and cover them with boiling water from the potatoes.
4. Let the asparagus stand for about 1 min., then drain and rinse in cold water. Meanwhile let the potatoes steam off.
5. For the marinade: Combine the ingredients in a large bowl.
6. Pour 2 tbsp of the marinade over the cheese, then cover and refrigerate for about 20 min.
7. Coat the warm potatoes in the rest of the marinade, cover, and refrigerate, as well.
8. Arrange the potatoes, peas and asparagus in layers in a large, flat serving dish.
9. Sprinkle the cheese over the potato salad along with the chopped white onions.
Any leftover potato salad makes a lovely packed lunch. Place in a small container and eat on its own or together with a cold, roasted chicken drumstick and some bread. If you like, you can substitute broccoli in small florets for the asparagus, and use cheese in cubes instead of block cheese.