In a large cast iron skillet, melt the butter over medium-high heat. Add the carrots, lower the heat to medium, season with sea salt and pepper, and let cook, tossing often, for approximately 6-7 minutes, depending on the size and shape of your carrots. The goal here is to soften the carrots.

Add the grapefruit juice and the maple syrup. Toss well so all the carrots are coated. Cook until the liquid turns into a glaze, about 15 minutes. Coat the carrots with the glaze using a spoon while cooking. Remove to a serving platter, garnish with fresh thyme sprigs and a small pinch of sea salt, and serve immediately.