Preheat the oven to 200ºC.
Add the tofu, mushrooms and onion to a baking dish, drizzle with olive oil and the paprika, salt and pepper and bake for 40 mins, stirring at the 20 minute mark, until the liquid from the mushrooms has evaporated and everything is golden.
Add the potatoes to a lined baking tray, drizzle with oil and bake for 50-60 minutes until a sharp knife goes through easily. Allow to cool a little.
Add the flour, mustard, sour cream, stock and MSG to the baking dish with the mushroom mixture and stir everything together until combined. Bake for a further 20-30 minutes until reduced to a nice thickness. Stir through the parsley, taste and season.
When the potatoes have cooled a little, peel the skins, using a clean tea towel to handle if still too hot. Pass the flesh through a sieve into a saucepan or add to a small saucepan and mash very thoroughly until smooth. Add the butter, milk and a generous pinch of salt and combine. If cooled too much then warm on a low heat in the saucepan.
Plate up the sweet potato mash and stroganoff, garnish with more parsley if desired.
