Preheat oven to 250° F. Place tomatoes in a mixing bowl. Add oil, herbs, garlic and seasoning, then mix to combine. Spread the mixture on a parchment lined baking sheet and slow roast for 30 minutes. Turn the oven off and leave the tomatoes in the oven while you prepare the rest.
Place cauliflower and garlic in a pot, cover with cream and season well. Bring to a simmer and cook until the cauliflower is soft, about 15 minutes. Strain the cauliflower, reserving the cream, and put in a blender. Blend until smooth, adding in some of the reserved liquid as needed to create smooth consistency.
Lightly oil the grill and grill fish for 7 minutes. Turn and drizzle with butter. Continue cooking for another 7 minutes, or until easily flaked with a fork. Set aside.
Mix the vinaigrette ingredients together in a small bow. Taste and adjust seasonings if necessary. Set aside.
Place a big spoonful of the mash in the center of a plate. Add the fish on top, and arrange the dried tomatoes around it. Drizzle the vinaigrette over the dish and serve. Garnish with micro greens (optional).