Preheat the oven to 400°F.

Wash beets well and pat dry. Place them on a large piece of aluminum foil on top of a baking sheet. Drizzle the beets with the olive oil, and rub to coat each beet thoroughly. Season the beets well with salt and pepper. Bring the edges of the foil up over the beets and fold together, then fold the side edges together to make a fully enclosed packet. Place the beets in the oven and bake until they are tender when pierced with the tip of a knife, 1 to 1 1/4 hours, depending on the size of the beets.

Remove the beets from the oven and set aside until cool enough to handle, then rub the skins off completely using paper towels. Place the beets in the refrigerator until chilled.

While the beets are chilling, make the vinaigrette:  Combine the vinegar, onion, garlic, mustard and honey and let sit for 5 minutes. Whisk to combine, and then add the oil in a thin, steady stream while whisking continually until the dressing is emulsified. Stir in the herbs and season the dressing with salt and pepper to taste.

Once the beets are chilled, slice them into 1/4-inch slices. Arrange a few leaves of Bibb lettuce on salad plates, and top with a few leaves of the mixed lettuces. Divide the beet slices between the plates and spoon the dressing over the beets and lettuces. Sprinkle the feta over the beets and then garnish with the pistachios. Serve immediately.