Preheat the oven to 450 degrees F, and adjust a rack to the top third.
Cut off the stems and greens from the Kohlrabi (saving them for another use, like stock and/or a stir-fry), and then peel them. Cut about 1/2-inch off each end, and then cut them into approximately 1/2-inch slices, horizontally. It’s important that they’re not too thin!
Generously drizzle olive oil on a sheet pan and then dredge each Kohlrabi slice in the oil to coat both sides. (They should not be “swimming” in the oil — just well coated.) Season both sides with salt and pepper, arranging them on the pan with about an inch between them.
Place the sheet pan in the preheated 450 degree F oven and roast until golden brown on the surface, and tender on the inside, about 8 to 10 minutes on the first side, and about 4 to 6 on the second. You can test them with a fork – it should slide out easily when they're done.