Mustardy Quorn and mushroom stroganoff

Fry the shallots in calorie controlled cooking spray in a non-stick frying pan for 2 minutes. Add the garlic, mushrooms and 1 tablespoon of the stock and cook for 3 minutes, stirring.Pour the rest of the stock into the pan and add the Quorn pieces plus seasoning. Bubble the stroganoff for 5 minutes.Remove the pan from the heat and leave to cool for 5 minutes. Stir the mustard and the yogurt into the stroganoff, off the heat. If you add the yogurt to the sauce when it is straight off the boil, the yogurt will split and the sauce will curdle, so by allowing it to cool a little first, you should end up with a smooth creamy sauce, but without making the whole dish too cold. Sprinkle the tarragon and lemon zest over the stroganoff before serving.Serve this creamy stroganoff with brown rice (50 g (1 3/4 oz) dried weight)and a generous dollop of Greek yogurt.