Trim off the greens and the root ends of the beets. Scrub the beets well under cold water and pat dry. Leave the skins on.
Slice the beets into thin rounds using a mandolin. Aim for about 1/16-inch—thin, but not paper-thin. If they’re too thin, they won’t be sturdy enough for dipping (especially with a thicker dip like green goddess ranch).
Add the beet slices to a large bowl, sprinkle with the 1/2 teaspoon kosher salt, and toss to coat. Let sit for 15 minutes to release excess moisture.
Line a baking sheet with paper towels, arrange the beet slices on the paper towels and cover with another layer of paper towels to pat them dry.
Return to a clean, dry bowl, drizzle with 1 tablespoon olive oil and toss until evenly coated.
Heat the oven to 300°F. Line 2 baking sheets (or more) with parchment paper. Lay the slices in a single layer with space between them—no overlapping. (You’ll likely need to bake in batches.)
Bake for 25 minutes, flip the slices, then bake for another 20-30 minutes, or until the chips look dry, slightly wrinkled at the edges, and crisp. Start checking early—beets can over-brown quickly, and some slices may finish before others.
Let the chips cool on the baking sheets for a few minutes, then transfer to a wire rack to finish crisping.
While still warm, season with flaky sea salt and black pepper or sprinkle with the optional seasoning options.
Store in an airtight container for up to a week. The beet chips will eventually loose their crispiness, you can recrisp them in a 300°F oven for 10-15 minutes.