2 tablespoons vegetable oil
2 tablespoons fish sauce
2 tablespoons water
1 1/2 tablespoons sugar
1 teaspoon salt
2 green onions, white parts only, thinly sliced
vegetable oil, for brushing
Prepare charcoal grill or preheat an ungreased cast-iron skillet over medium heat. Very lightly brush the corn with oil and set on the grill rack or in the skillet. Cook, turning every 2-3 minutes, until the kernels are tender and nicely charred, 12-15 minutes total; keep warm. Meanwhile, in a bowl stir together the fish sauce, water, sugar and salt until it is dissolved. Heat the 2 tbsp oil in a saucepan over medium heat until very hot but not smoking. Carefully pour liquid mixture in (it may sputter a bit so watch out); add the green onions and simmer until the sauce begins to thicken, about 30 seconds; remove from heat and cool. Brush cooked corn with the sauce and serve.