Combine first 3 ingredients in a medium bowl, stirring with a whisk.
Combine onion and next 6 ingredients in another medium bowl, stirring with a spoon. Add rice; stir gently. Cover and keep warm.
Heat a large nonstick skillet over medium heat. Coat pan with cooking spray. Add egg mixture to pan; cook over medium heat 2 minutes. Do not stir until mixture begins to set on bottom. Draw a heat-resistant spatula through egg mixture to form large curds. Do not stir constantly. Egg mixture is done when thickened, but still moist. Remove from heat.
Warm tortillas according to package directions. Spoon scrambled egg evenly over tortillas; top evenly with rice mixture, and fold in half. Serve with lime wedges, if desired.