• Stir together vinegar, soy sauce, olive oil, brown sugar, smoked paprika, mustard powder, chili powder, garlic powder, onion powder and pepper in 13- x 9-inch baking dish. Toss with mushroom slices until well coated. Cover and refrigerate for at least 8 hours or overnight.
• Preheat oven to 250°F. Arrange sliced mushrooms in single layer, without overlapping, on 2 parchment paper–lined baking sheets, each fitted with wire rack.
• Bake, rotating pans halfway through, for 1 1/2 to 2 hours or until mushrooms are dried and shrunken, and edges are crisp with a chewy texture. Let cool completely. Can be refrigerated in airtight container for up to 5 days.

Tip: Alternatively, use a dehydrator according to manufacturer’s instructions.