Homemade Gefilte Fish

Name: Homemade Gefilte Fish
Ingredients: * 1 quart fish stock (homemade or store bought); * 1 clove garlic, crushed; * 1 celery heart, sliced; * 1/2 a lemon; * salt and pepper; * for the gefilte fish:; * 3/4 pound boned salmon; * 3/4 pound boned whitefish (turbot, cod, pike, etc ); * 1 tablespoon vegetable oil; * 1 medium onion, fine diced; * 2 large egg; * 1/2 cup matzo meal; * 1/2 cup chopped parsley; * 1/2 teaspoon ground black pepper; * 1 teaspoon salt; * horseradish sauce:; * 1/2 cup sour cream; * 1/3 cup horseradish; * 3 tablespoon chopped fresh dill; * salt to taste