Wash and chop the potatoes. You pick the size, but keep it consistent so they cook at the same speed.
Heat the canola oil and butter over medium heat. Add the potatoes and salt and stir to cover with oil.
Cook until the potatoes are mostly soft, about 15-20 minutes depending on their size. Stir occasionally, but you should have enough oil that they don't stick.
When the potatoes are almost cooked through, add the water and increase the heat. Cook until the water is evaporated and the potatoes are cooked through, stirring often to distribute some of the potatoes' starch.
Taste and adjust seasoning if necessary, and serve.