Chop onion, celery, garlic.
Combine in a microwaveable dish; add a dash of olive oil and microwave, covered 7 minutes.
Using kitchen shears, cut tomatoes into large pieces.
Drain corn and beans.
Combine tomatoes, corn and beans in a large bowl with taco seasoning and onion mixture.
Combine half of the vegetable mixture and half of the rice in a baking dish.
Top with a layer of ham or chicken.
Combine remaining vegetable mixture and rice and place as top layer of casserole.
Cut green pepper in strips and microwave, covered, about 4 minutes. Place on top of casserole.
Top entire casserole with cheese.
Bake at 350º until center cheese is melted.
May be frozen before or after baking.
Serves approximately 30.