Heat oil and butter in a large pot over medium-high heat. Brown meat in two batches, setting aside on a plate when brown. Cut pieces in half. Set aside.
Add diced onions to the pot. Stir and cook for two or three minutes until softened, then add garlic for another minute. Pour in beef stock, then add Worcestershire, tomato paste, paprika, salt, pepper, and sugar. Add beef back into the pot. Stir to combine. Cover and simmer for 1 1/2 to 2 hours.
: The liquid should cook down to a thicker state. If it gets too thick/reduces too much, add additional water as needed.
Add carrots and potatoes, then cover and cook for an additional 30 minutes. (If stew gets dry, just add a cup of hot water at a time to replenish the liquid.) Taste and adjust seasonings as needed.