Peel the sausage and cut into thin slices.
Peel the lower third of the asparagus and cut off the woody ends. Clean the green beans and cut both vegetables diagonally into pieces.
Blanch the asparagus and green beans for 4-5 minutes in boiling salted water.
Drain, rinse in cold water and drain well.
Wash the peppers, halve, deseed and cut into strips, then into diamonds. Wash and thinly slice the radishes.
Wash and halve the tomatoes.
Rinse the white beans in a sieve and drain.
Peel and thinly slice the onion.
Mix together all salad ingredients in a large bowl.
Whisk together the vinegar, stock, mustard, a pinch of salt, paprika and sugar.
Gradually whisk in the oil to make a dressing. Season to taste.
Drizzle the dressing over the salad, mix well and chill for 1 hour before serving. Season and serve sprinkled with parsley.