Bring a large pot of salted water to a boil over high heat on the stove.
In a medium, heavy saucepan over high heat on the stove, combine 240 milliliters of the bourbon, the corn syrup, brown sugar, butter, and mint. Bring to a boil, stirring until the sugar dissolves. Continue boiling until the syrup is reduced and thickened enough to coat the back of a spoon, about 8 minutes, stirring occasionally. Set a strainer over a measuring cup or small bowl and strain the glaze, pressing down to release all of the glaze (you should have about 180 milliliters). Mix in the remaining 1 tablespoon bourbon, the vinegar, ⅛ teaspoon salt, and ⅛ teaspoon pepper. Put half of the glaze into a small saucepan.
Cut the yams diagonally into 12-millimeter slices, each about 7.5 centimeters long. Cook the yams in the pot of boiling water until just tender but not falling apart, 7 to 8 minutes. Drain thoroughly. Brush the yams generously on both sides with the remaining glaze and season each with a pinch of salt and pepper.
Prepare the grill for direct cooking over medium heat (180° to 230°C).
Prepare the grill for cooking over medium heat (200°C).
Brush the cooking grates clean. Grill the yam slices over direct medium heat, with the lid closed, until well marked and heated through, 4 to 5 minutes, turning once. Transfer to a platter. Warm the glaze in the saucepan over medium heat. Drizzle the glaze over the yams and top with the mint. Serve warm.
Brush the cooking grates clean. Grill the yam slices over medium heat, with the lid closed, until well marked and heated through, 4 to 5 minutes, turning once. Transfer to a platter. Warm the glaze in the saucepan over medium heat. Drizzle the glaze over the yams and top with the mint. Serve warm.
