Put oil in a heated pan.
Saute the garlic under medium heat.
When the garlic turns golden, put in the onions.
When the onions sweat and wilt, put in the pork.
Cook the pork for 20-30 minutes. Season the pork with 1 tbsp fish sauce.
Put in the tomatoes. Stir well.
Add in the pork liver. Stir for 2-3 minutes.
Just when the liver changes color, put in the water and the tomato sauce.
Add in the carrots and potatoes.
Lower the heat.
Cover the pan. Let it simmer for 20 minutes to allow the meat to tenderize.
Stir occasionally (every 10 minutes, or so) to prevent burning the bottom of the pan.
When the meat is tender enough, season with additional fish sauce, salt, and pepper.
Add in the bell peppers.
Turn off after 3-5 minutes.
Serve with hot rice.