Vegetable Grain Casserole

My friend gave me this recipe, and told me to make it, for her. So, I did.
Vegetable Grain Casserole

2 tsp canola oil
1 small uncooked onion(s), chopped
1 clove(s) (medium) garlic clove(s), minced
2 cup(s) frozen corn kernels, thawed and drained
3 cup(s) uncooked Swiss chard, thick stems removed, coarsely chopped
14 1/2 oz canned diced tomatoes, with chilies, well-drained
2 cup(s) cooked barley (I used buckwheat. I had it.), quick-cooking recommended
1/4 tsp Cumin seeds
1/2 tsp table salt
1/4 tsp black pepper, freshly ground
2 spray(s) cooking spray
1/2 cup(s) low-fat shredded Cheddar cheese, sharp-variety recommended


Instructions
Preheat oven to 350ºF.


Heat oil in very large nonstick skillet over medium heat. Add onion, garlic, corn and Swiss chard; cook, stirring frequently, until onion is translucent and Swiss chard is tender, about 5 minutes. Stir in tomatoes, barley, cumin, oregano, salt and pepper; heat through.


Coat a 2 1/2- to 3-quart baking dish with cooking spray. Spoon barley mixture into prepared dish in an even layer; sprinkle with cheese. Bake until cheese melts and mixture is hot, about 25 to 30 minutes. Remove from oven and let stand for 5 minutes before slicing into six pieces. Yields 1 piece per serving.