In a large pot, add rice and at least 4 cups water.
Bring rice to a boil, then turn heat to medium and allow it to simmer for about 30 - 40 min. When rice is just barely cooked, from the heat and drain any remaining water, or use a slotted spoon to scoop it out.
While rice is cooking, heat oil in a large frying pan on medium-high heat.
Add all sliced peppers and onions to the pan at once and stir. Toss in oregano and some salt.
Keep stirring frequently until peppers are just soft enough to be poked with a fork, but still firm/tender. Set them aside for a minute.
To serve, scoop the rice onto a plate or into a container and top with fajita veggies.