Add garlic cloves, Thai chili peppers, kosher salt, and msg to a mortar1.
Using a pestle, crush the ingredients until a rough paste forms.
Next add in ¼ cup of the fish sauce, two tablespoons of sugar, and the lime juice. Mix until well combined.
Taste the dipping sauce and adjust it to your liking. Add more fish sauce if you want it saltier, more sugar if you want it sweeter, or more lime juice if you want it tangier.
Stir in the chopped cilantro and serve.