Heat the oil in a alrge wok or pan and saute the onion until translucent. Add the diced green and red peppers and saute until tender. Reduce the heat and stir in the corn, rice, and finally the guava. Remove from heat and season to taste. Chill in the refrigerator and stir again before serving. For a flavor accent, you may toss in a vinaigrette dressing. Each serving contains 372 calories, 0 cholesterol, 16 grams fat, 6 grams protein.