Heat the butter and olive oil in a large skillet over medium heat. Add the onion and carrots; cook and stir until tender. Season with curry powder, turmeric, salt, pepper, and red pepper flakes.
Add the cauliflower and potatoes to the pan, and stir to coat with spices. Reduce heat to medium-low, cover, and simmer for 20 minutes, or until the potatoes are tender. Stir occasionally.
