Heat oil in a large pot over medium-low heat. Add onion, carrot, celery, salt and pepper. Cook for 5 minutes.
Stir in garlic and cook until fragrant. Add flour, stir, and cook for 1 minutes.
Add potatoes, broth, and milk. Bring to a simmer over medium-high heat. Reduce to a simmer, cover, and cook for 15 minutes. Stir occasionally, scrapping bottom of the pot.
Add salt and pepper to taste if needed.
Serve with optional toppings.
Notes
Optional Toppings: cheese, green onions, crumbled bacon, sour cream