Cook the diced potatoes and swede/sweet potato in boiling water until soft and mashable
Break the nori sheet into small pieces and pop in a small bowl. Cover with hot water and leave to soften.
Heat a couple of tablespoons of water in the base of a medium-sized pan (ideally oven proof so you don’t need to transfer it and create more washing up!) and add the onion, leek and carrots plus a pinch of salt. Pop on the lid and sweat the veggies on a medium/low heat for approximately 10 minutes until they are beginning to soften.
Add the mushrooms to the pan and cook for another 5 minutes before pouring in the cream along with the tofu, tarragon and peas. Stir well and simmer for a couple of minutes.
Drain the nori and squeeze it in the sieve to get rid of most the water. Add it to the pan and mix well. Simmer for another minute then turn off the heat and season with salt and pepper to taste.
Pre-heat the oven to 180ºC.
By now the potatoes and swede should be ready so drain off the water and return the veg to the pan to mash – add a little dairy-free milk and seasoning if you desire.
Spread the mash over the top of the no-fish mix and fluff up with a fork to make little peaks.
Place in the oven and bake for 15-20 minutes until the mix is bubbling up and the mask starts to brown. Alternatively, you can place directly under a pre-heated grill and brown the top that way.
Serve with extra greens on the side.