Simmer 2 cups water and put in the bouillon. Turn to low.
Meanwhile slice portobello very thin into slices like sandwich meat. Save and mince the stem of the shroom then put it into the broth that is simmering.
Heat pan with oil to medium heat and add onion. Let fry for about 1 minute and then add mushroom slices. Squirt Braggs evenly covering all slices and onion then turn them over. Let the mixture sizzle for about 1 more minute or until it caramelizes.
Turn on oven broiler to about 400 degrees.
Cut "cheese" and put it on one side of halved bread and put the mushrooms and onions on the other side.
Put under the broiler for 1-2 minutes or until sandwich is toasty and yummy.
Strain shroom stems out of broth and serve the broth in a bowl on the side. Dip your sandwich in and munch.