Heat the oil with the clove of garlic and sage. Remove the garlic clove.
Turn the seitan schnitzel in the flour and fry lightly on both sides for 10 to 15 seconds. Add salt, pepper and the vegetable stock with half of the lemon juice and the grated lemon zest. Simmer for 5 minutes until the liquid becomes creamy.
Add the rest of the lemon juice and soy sauce and season well with salt and pepper.
Serve the seitan schnitzel garnished with parsley. Serve with rice and or vegetables.