Portobello Stuffed Manicotti with Creamy Sun-Dried Tomato Sauce

1) Boil the pasta shells in salted water until al dente according to package instructions. Set aside.
2) For the filling, saute the mushrooms and onion in oil over medium heat until they soften (about 5 minutes). Set aside for the moment. Blend all of the remaining filling ingredients in a blender until smooth, but thick. In a bowl, fold the mushrooms/onions into the cashew blend. Place a generous amount into each pasta shell (I like to place the filling in a Ziplock bag, cut off one of the corners, and squeeze it into the individual shells). Place the shells in a lightly greased 9 x 13 glass baking dish. Set aside.
3) For the sauce, saute the soaked (and drained) tomatoes in the margarine over medium heat (if they are too big, slice them finely). Saute for about 3 minutes. Add herbs and saute for an additional minute. Add garlic and salt and pepper to taste and allow to simmer for about 5 minutes (or until it condenses slightly). Whisk together the reserved tomato water and arrowroot powder, and add to the simmering sauce. Allow to simmer for an additional minute, or until thickened. Add the vinegar. Pour over top of the manicotti. Sprinkle with vegan cheese, if desired. Bake in a 350 degree F oven for 30 minutes. Serve, and enjoy!