Position a rack in the center of the oven and heat the oven to 450°F. Trim, peel, and cut the beets into 1-inch wedges. Discard the greens or save for another use. Put the beets in a shallow 9x13-inch (or similar) baking dish, toss them with the olive oil and salt until thoroughly coated, and then arrange them in a single layer. Roast the beets, stirring after 20 minutes, until tender when pierced with a fork or skewer and lightly browned on the edges, 30 to 40 minutes.
Meanwhile, whisk the orange juice, vinegar, lemon juice, salt, and pepper in a small bowl until the salt is dissolved.
Remove the beets from the oven and while they’re still hot, drizzle the dressing over them, tossing to coat. Let the beets cool to room temperature to meld the flavors. Taste and add more salt, if necessary. Serve at room temperature or gently warmed, topped with the chives, if using.