In a large pot, heat oil.
Add onion and saute until softened.
Add cabbage and cook on medium heat, stirring occasionally, until softened – about 5-8 minutes.
Add rice and cook for about 2 minutes, while stirring to well coat the rice.
Add tomatoes, 2 ½ cups water and oregano.
Bring to a boil.
Reduce to a simmer and cook, covered, for 20-25 minutes, until rice is soft.
Add cheese and salt. Stir to combine.