Heat canola oil in a skillet over medium-high heat. Cook and stir onion and potato in hot oil until lightly cooked, about 2 minutes. Stir rice into onion and potato until rice is golden, 2 to 4 minutes.
Pour water, tomato sauce, and chicken bouillon into vegetable and rice mixture; stir and bring to a rolling boil. Cover, reduce heat to medium-low, and cook at a simmer until rice is tender, about 15 minutes.
