In a large frying pan boil the 7/8 C water. Then add the TVP, stir, and let sit for 5 minutes. Preheat the oven according to the directions for the taco shells.
Optional step: Meanwhile chop up some onions (~ 1/2 C chopped) and mushrooms (about 8). Heat some oil in a small frying pan then saute the onion and mushrooms.
Put the shells in the oven. Add the seasoning mix to the large frying pan along with the 2/3 C water (or whatever amount of water the packet calls for). Cook over medium heat until thickened.