1.5 pounds red beets – greens trimmed to 1 inch, scrubbed
water – for boiling beets; reserve 0.75 cup for sauce
0.5 cups granulated sugar
0.5 cups apple cider vinegar
1.5 tbsp cornstarch
0.5 tsp kosher salt
0.25 tsp black pepper
2 tbsp unsalted butter
Instructions
Place the red beets in a large pot in a single layer. Cover with water by about 1 inch.
Bring to a boil over high heat, then reduce to a simmer. Cook until tender when pierced at the center with a knife, 45–60 minutes depending on size.
Using tongs, transfer beets to a bowl. Reserve 0.75 cup of the beet cooking liquid, then drain the rest. Let beets cool just enough to handle, slip off skins, and slice into 0.25-inch rounds or wedges.
In a medium saucepan off heat, whisk together the granulated sugar, apple cider vinegar, reserved 0.75 cup beet cooking liquid, cornstarch, kosher salt, and black pepper until smooth.
Set the pan over medium heat and cook, stirring constantly, until the mixture comes to a simmer and thickens to a glossy sauce that coats a spoon, 2–3 minutes after it starts bubbling.
Add the sliced beets to the saucepan and simmer gently, stirring occasionally, until heated through and evenly glazed, 5–8 minutes.
Remove from heat and stir in the unsalted butter until melted. Let stand 5 minutes for the flavors to meld, then serve warm.