In a medium pot, heat oil over medium-high. Add carrots and onion, season with salt and pepper, and cook until onion is translucent, 5 minutes. Add flour and stir to coat. Stirring constantly, slowly add broth and 2 cups water. Add potatoes and bring to a boil over high; reduce to a rapid simmer and cook, stirring occasionally, until carrots and potatoes are tender, 15 minutes. Add brisket and peas and cook until heated through, 3 minutes.