Preheat oven to 400°.
Heat a small skillet over medium-high heat. Coat pan with cooking spray. Add onion; sauté 8 minutes or until tender. Remove from heat; cool.
Lightly spoon flour into a dry measuring cup; level with a knife. Place flour, oats, baking powder, salt, and pepper in a food processor; process until oats are coarsely ground (about 10 seconds). Add butter; pulse 3 times or until combined. Add onion and cheese; pulse 3 times or until blended. Place mixture in a medium bowl. Add 1/4 cup water and egg substitute, stirring until moist. Let mixture stand 1 minute.
Place mixture onto a lightly floured surface; knead lightly 3 times (dough will be sticky). Divide dough in half; press each half into a 5-inch circle. Cut each circle into 8 wedges. Place wedges on a baking sheet coated with cooking spray. Bake at 400° for 15 minutes or until lightly browned. Serve warm.