Marinate chicken pieces in soy sauce and lemon juice for half an hour. Drain chicken from the marinade.
In a heavy pan, heat oil over medium-high heat. Sauté garlic, onions, and tomatoes for 2 minutes or until onions are soft.
Add chicken pieces and saute for a few minutes until meat is nicely browned and no longer pink.
Add fish sauce, stir and then add tomato sauce and water. Let the mixture boil and then reduce heat, cover and let simmer, stirring occasionally for 20 minutes.
Add carrots, pepper, and potatoes; cover and cook for 10 minutes or until potatoes are tender.
Season with salt and pepper, to taste.
Serve with steamed rice. Enjoy!