Melt the butter along with 1 teaspoon of the chopped thyme in a large, deep sauté pan over medium heat. Once the butter has melted, add enough water to barely cover the bottom of the pan.
Lay the corn & onions across the bottom of the pan and season with salt and pepper.
When the water simmers, cover the pan and cook, shaking the pan occasionally, until the corn is tender, 8-10 minutes.
Remove the corn, keeping the cooking liquid in the pan. (If it looks like there's more than 2-3 tablespoons of liquid left in the pan, increase the heat to reduce the liquid.) Stir in the remaining thyme and drizzle the cooking liquid over the corn.