Preheat the oven to 350 degrees F (175 degrees C).
Heat oil in a large lidded pot over medium heat. Add chuck roast and brown, turning occasionally, about 5 minutes. Spread horseradish on roast. Add water and cover the pot.
Bake in the preheated oven for 2 hours.
Remove from the oven and leave oven on. Transfer roast to a plate. Add carrots, potatoes, and onion to the pot and return roast to the pot. Cover and continue baking about 1 hour more.
