Celery and apple salad - Recipe from South Tyrol

Ingredients

• 1 small stick of celery
• 2 dspn lemon juice
• 1 Pinch salt
• 2 egg yolk
• 1 tsp hot mustard
• 1/2 tsp lemon juice
• 1/2 tsp Worcester sauce
• 2 dspn raspberry vinegar
• salt, pepper
• 250 ml oil
• 250 ml sour cream
• 2 apples
• 100 g walnut kernels
• lettuce leaves and hearts
• parsley (chopped)