1. Heat oil in large skillet over medium heat. Add onion and garlic, and season with salt, if desired. Cook, covered, 8 minutes. Add sweet potatoes, jalapeño, cumin, and oregano; cover, and cook 10 minutes, stirring often. Stir in corn, and cook 1 minute, or until heated through. Season with salt and pepper, if desired.
2. Spread 1/2 cup filling on one-half of each tortilla, leaving 1/2-inch border around edges. Fold tortillas to enclose filling. (If a tortilla’s edges don’t stick together, brush some oil along bottom inside edge.)
3. Coat large skillet with cooking spray, and heat over medium heat. Cook quesadillas in skillet 2 to 3 minutes, turning once.