1. In a large cooking pan, heat 1 or 2 tbsp vegetable oil and fry the garlic until fragrant. Add the beef and cook for a few minutes. Add carrots and onions, continue stirring until the beef is almost cooked through.
2. Add water and ingredients A, turn the heat to high and bring it to a boil. Once it boils, reduce the heat to medium-low. Add "curry roux" and stir until the roux has dissolved completely. Turn the heat to low and add the leeks. Cook for a few more minutes, stirring occasionally to prevent ingredients from sticking to the bottom of the pot.
3. Meanwhile, boil enough water in a large pan and follow the udon package directions to cook them. Drain and divide the udon into each serving bowls.