Heat a pan over medium high heat.
Add about a tablespoon of cooking oil. When oil is hot, add garlic, onion , saute for about a minute then add the ground pork.
Cook until pork is browned then add diced tomatoes. Cook for about 5 minutes or until tomatoes are wilted.
Season with fish sauce and or salt and ground black pepper according to your taste.
Add 1 cup water and bring to a boil, lower heat and let it simmer until liquid is greatly reduced or almost gone, then add sliced chayote then add 1/2 3/4 cup water, bring to a boil again and let cook until chayote is tender and liquid is reduced.
Taste and adjust seasoning as necessary. Turn off heat...it's done.
Serve with steamed rice and pair it with fried or grilled fish or meat.