Cut the tomato into quarters, then halve each piece. Tear the lettuce into bite-sized pieces. Cut the vermicelli into shorter lengths using kitchen scissors.

Add the seasoning ingredients (water, salt, pepper, soy sauce, chicken stock powder) to a pot and heat over medium heat until boiling. Add the vermicelli and simmer on low heat for 4 minutes until cooked.

Add the tomato and lettuce to the pot and cook until the lettuce softens. Drizzle sesame oil over the soup.