Step 1

Prepare a grill for medium-high heat. Rub sweet potatoes with 2 Tbsp. oil and wrap tightly in foil—you can wrap them on their own or put 2 in each packet. Grill, turning every 5 minutes or so, until tender, 30–45 minutes. Unwrap and let cool slightly. (Or, steam in a basket set over a pot filled with 1" of boiling water 30–35 minutes. If not using right away, let cool, then cover and chill until ready to grill—up to 2 days.)

Step 2

Meanwhile, bring honey, vinegar, and a big pinch of kosher salt to a boil in a small saucepan over medium-high (you can do this on the grill if you want), reduce heat, and simmer until just beginning to thicken, about 4 minutes. Keep warm.

Step 3

Cut sweet potatoes in half lengthwise. Rub cut surfaces with 1 Tbsp. oil total; season with kosher salt. Grill, cut side down, without turning, until lightly charred, about 5 minutes. Transfer to a cutting board and brush with honey glaze.

Step 4

Arrange sweet potatoes on a platter and drizzle with more glaze and remaining 1 Tbsp. oil. Season with sea salt and pepper.