Preheat oven to 400F. Line a large baking sheet with parchment paper.
Combine sliced mushrooms, olive oil, salt and smoked paprika in a bowl. Toss carefully until well coated.
Transfer the mushrooms to the lined baking sheet and bake for 20 minutes. Turn them over and bake the other side for an additional 15 minutes. Turn off the oven and let them sit for 15 minutes.
Spread 1 teaspoon of mustard on each slice of bread. Top each one with 2 tablespoons of Shreds and place in the toaster oven until the cheese is melted and the bread is slightly toasted (you can also put them in the oven at 400F for about 4 minutes)
To assemble the open faced sandwich, top each toasted slice of bread with 2 mushroom slices, 2 tomato slices, 2 avocado slices and shredded lettuce. Sprinkle 1 teaspoon of Shred on each one and place them in the oven or toaster oven just until the cheese melts. Serve immediatelyRecipe by: May I Have That Recipe