Prepare Toasted Mustard Seed Aïoli; set aside.
Combine egg substitute, salt, and pepper. Place a small skillet over medium heat until hot. Add 1 teaspoon butter to pan; pour 1/4 cup egg mixture in center of pan. Do not stir. Cook until almost set; turn egg, and cook 30 seconds. Remove from heat, and keep warm. Repeat with remaining butter and egg mixture.
Spread 1 tablespoon Toasted Mustard Seed Aïoli on bottom half of each bagel; add cooked egg, and top each evenly with tomato and spinach. Top with remaining bagel half.