Place the soy milk, mustard, parsley, lemon juice in a blender.
With the blender running, slowly add the oil. It should be thick and creamy when all the oil is added. Add some salt and pepper. Taste and adjust seasoning (salt, pepper and lemon juice) as desired.
Pour into a container and add smoked paprika as desired. The more added the stronger the smoky flavor. I started with ¼ teaspoon amd then added more.
Refrigerate until ready to serve the sandwich.
Makes about one cup. Save leftovers in an airtight container for five days. Use it as a sandwich spread, french dip or salad dressing within the five day window.
Prepare mushroom filling
Preheat oven to 400 degrees F.
Slice the mushrooms into moderately thin slices. Place into a medium bowl.
Cut the onion in half and then slice each half into thin pieces. Add to the bowl.
Add the fresh thyme and olive oil. Sprinkle lightly with salt and pepper.
Layout on a baking sheet and place into the oven to cook for 15 minutes or until onions and mushrooms are slightly browned.
When ready, remove from the oven and drain if needed.
When ready to serve, place the flatbreads in the oven to heat for a few minutes.
Layout flat and cut in half down the middle. Layer ingredients on one half of the flatbread starting with the spinach followed by mushrooms and onion mixture and topped with the avocado slices and sprouts.
Place top on sandwich and cut in half. Serve with 2 tablespoons mayonnaise per sandwich on the side to dip or inside the sandwich.
Tips for BEST results:Eat the smoky mayonnaise within 3-5 days of making it. I find that the vegan mayonnaise loses its thickness easily over time, so it won’t last much longer than five days. Give it a good stir when you take it out of the refrigerator.The cooked mushrooms taste best warm or room temperature. Assemble your sandwich in the order shown, especially if transporting on the go so that the bread doesn't get soggy. Wait to add mayonnaise until you get ready to eat.Take note of the moisture on your mushrooms when they come out of the oven. If they appear extra wet, it's a good idea to drain them for a few minutes to prevent them making the sandwich soggy.Nutrition info based on one sandwich with 2 tablespoons of smoky paprika mayo.