Cook rice in oil until lightly browned.

Chop onion, green pepper, and celery.

Add the chopped vegetables to the browned rice and sauté briefly.

Stir in the canned tomatoes.

Bring the mixture to a boil.

Reduce heat to low, cover the pot, and cook for about 25 minutes, or until the rice is tender and the liquid is absorbed.

Add cubed ham to the rice.

Heat until the ham is hot and the flavors are well combined.

Serve hot.