Microwave the potatoes: add the quartered potatoes into a bowl and cover it with plastic wrap. You can place a larger dish on top of the bowl to save the wrap for other uses. Place it into the microwave and cook for 7 minutes.
Season and mash the potatoes: remove the plastic wrap/dish and add 1/4 tsp salt, 1/4 tsp pepper, 2 tbsp butter. Use a fork to mash the potatoes and mix well.
Poach the salmon: add 1 cup water, 2 oz whole celery, 2 oz whole carrots, 2 oz diced onions, 2 bay leaves, 0.25 oz dill, 1/4 tsp salt to a pot and bring it to a boil. Turn the heat down to low and add the fillets. Put on the lid and simmer the fillets for 5 minutes. Turn off the heat, carefully take out the fillets and leave aside.
Make the cream sauce: remove the herbs and vegetables from the pot and reduce the infused stock to about 1/4 cup. Add 1/4 cup heavy cream, 1/4 cup whole milk, 2 tsp lemon juice, diced tomatoes, 1 tsp parsley and cook for 2 minutes over medium heat. Simmer some more if you want a thicker sauce.
Plate and serve: divide mashed potatoes into portions. Scoop one out and place it onto a serving platter. Flatten the surface, then place one fillet on top. Sprinkle with parsley and a dash of black pepper if desired. Place a lemon wedge and a sprig of parsley onto the platter to garnish and serve.