Trim and finely mince garlic cloves and chilies. Set aside.
Combine sugar and soda in a medium-sized bowl, stir briskly with a large spoon to dissolve sugar completely.
Once the sugar and soda have become one, add in fish sauce, chilies, and garlic and continue to stir until combined. Finally, add freshly squeezed lime juice. Sample the nước chấm and adjust the seasonings to taste---add more lime juice for sourness, fish sauce for saltiness, and sugar for sweetness.