Cook the pasta in boiling salted water for 12-15 minutes. Defrost peas. In the meantime, cut the sausage and gherkins into slices. Drain the pineapple and collect the juice.
Whisk the egg yolk and mustard with the whisk of the hand mixer. Gradually stir the remaining oil into the egg yolk mixture. Season to taste with salt, pepper, pineapple juice and gherkin liquid. Grate cheese into the mayonnaise.
Wash the salad, drain well and pluck into bite-sized pieces. Put all ingredients in a bowl and mix with the mayonnaise. Cover the salad and leave to stand for at least 30 minutes. Season to taste again before serving.