Whisk together the lime, warm water and sugar until the sugar has dissolved.
Slowly add the fish sauce, a little at a time until you reach your desired flavor. I find the amount in the recipe is perfect, but every one has their own tastes.
Add the chilies and garlic and let it stand for 20 minutes at room temperature before serving.
Store in an airtight container in the fridge for up to 6 months.
Notes
Adjust the amount of chilies to your spice preference. Remember that Thai chilies can be extremely spicy.
Use warm water to help the sugar dissolve.
Add the fish sauce slowly, tasting along the way, until you get the perfect flavor. You may have to add more/less depending on your preference.
For a sweeter nuoc cham, reduce the amount of fish sauce to 5 tablespoons.