Heat the sesame oil in a pot. Add the ground beef and sauté until browned. Finely chop the leeks and garlic, then add them to the sautéed beef. Stir in the tomato paste and cook thoroughly. Next, add the tomato purée, hot water, red pepper flakes, and salt. Mix well. Once the sauce thickens, add the noodles. Cook until the noodles are tender and well coated with the sauce. Serve with cheese or yogurt if desired. Enjoy!