How to Make It
Slice tempeh in half lengthwise; slice each half into 4 pieces, making 8 rectangles. Place in a small shallow dish; set aside.
Stir together Sriracha, vinegar, honey, and garlic in a small saucepan over medium. Cook, stirring often, until well combined and just simmering. Remove from heat; add butter, and cook, stirring until butter is melted and fully incorporated. Pour Sriracha sauce over sliced tempeh; let marinate 15 to 20 minutes.
Preheat oven to 425°F. Line a baking sheet with aluminum foil; set a wire rack on baking sheet, and coat with cooking spray.
Stir together flour, paprika, garlic powder, salt, and cayenne in a shallow dish. Stir together panko and cornmeal in a second shallow dish. Whisk together water, egg, and egg white in a third shallow dish.
Working with 1 piece at a time, let excess sauce drip from tempeh, reserving sauce for serving. Place tempeh in flour mixture, and coat evenly. Dip coated pieces in egg wash, and then dredge in panko mixture, pressing to adhere. Place breaded tempeh on prepared rack, and coat with cooking spray.
Bake in preheated oven, flipping after 12 to 15 minutes, and spraying again with cooking spray. Bake another 12 to 15 minutes or until golden. Serve immediately with reserved Honey-Sriracha Buffalo sauce. Serve with carrot and celery sticks, if desired.