Potato Salad with Horseradish

6 med. size boiling potatoes
1 c. finely chopped onion
2/3 c. chicken stock
1/3 c. olive oil
1 tbsp. white wine vinegar
2 tsp. prepared mustard
1 tsp. horseradish
2 tsp. salt
1 tsp. freshly ground pepper
1 tbsp. lemon juice

In a large pot, place unpeeled potatoes in enough lightly salted water to cover. Boil briskly until they show slight resistance when pierced with fork; do not overcook. Drain, peel and cut in 1/4 inch slices. Tightly cover and set aside.

Combine remaining ingredients, except lemon juice, in a saucepan and bring to a boil. Reduce heat, cover and simmer 5 minutes. Stir in lemon juice. Pour over potatoes and toss to mix. Cool before serving. Makes 6 servings.