Mushroom Stroganoff - Cooking like a Boss

50g 0.05kg 0.11lb 1.76oz butter	melt	cook til softened	fry on medium high til brown and limp	put asside	cook 1 min medium heat	low heat til thickened	serve
1 large onion	chopped
350g 0.35kg 0.772lb 12.3oz mushrooms	sliced
350ml 0.35l 23 ¹⁄₃tbsp 70tsp 1.48cup 0.616pint veg stock	boil down to 2/3rds
350ml 0.35l 23 ¹⁄₃tbsp 70tsp 1.48cup 0.616pint soured cream
3tbsp 0.045l 45ml 9tsp 0.19cup 0.079pint plain flour
4tbsp 0.06l 60ml 12tsp 0.254cup 0.106pint fresh parsley	chopped
300g 0.3kg 0.661lb 10.6oz rice	boiled and drained