Thaw K&N's Frankfurter Sausages as per instructions on pack, slice and set aside.
Sauté capsicums and mushrooms in 2 tbsp butter until tender, but not browned.
Push to one side and stir the flour in, making a roux. Cook flour on low heat for 1 or 2 minutes. Add cream, stirring continuously until thick and bubbly.
Add sliced Frankfurter Sausages and heat through, stirring occasionally.
Add lemon juice and spring onion leaves.
Whisk the egg yolk and paprika separately, and pour into the bubbling cream sauce all at once, stirring continuously until blended.
Immediately remove from heat. Sprinkle with red capsicum and serve.