1/2 cup pure maple syrup
1/2 cup red wine vinegar
Juice of 1/2 lemon, plus more as needed
1/4 cup sliced almonds, toasted
1/4 cup flat-leaf parsley leaves
Coarse salt and freshly cracked black pepper, to taste
Bring a saucepan of salted water to a boil. Fill a bowl with ice water and set aside. Using a mandolin slicer or very sharp knife, slice the beets into paper thin slices. Drop them into the boiling water and cook until softened but still firm to the bite, about 5 minutes. Transfer the beets to the ice water with a strainer and cool completely. Lay the slices out on a paper towel-lined plate to dry.
Meanwhile, bring the maple syrup and vinegar to a boil in a small saucepan over medium-high heat. Continue cooking until the liquid has large thick bubbles at the top and the liquid has reduced to about 1/4 cup. Remove from heat, squeeze the lemon juice into it and stir. Be careful it is extremely hot! Let the mixture stand until cool.
To assemble the carpaccio, lay the beet slices in a single layer, slightly overlapping, on each of 4 salad plates. Squeeze a little lemon juice over the parsley leaves and toss to coat. Drizzle about 2 teaspoons of the maple mixture over each plate of beet slices, followed by a scattering of parsley leaves and almonds. Lightly season each plate with salt and pepper and serve immediately.