Preheat oven to 400°.
Blanch brussels sprouts in boiling, salted water, drain and plunge into an ice water bath. Drain and dry.
Mix brussels sprouts with olive oil and vinegar, spread on a baking sheet lined with foil or parchment paper. Season with a sprinkling of sea salt and fresh ground pepper.
Roast for 45 minutes, or until fork tender, turning several times during cooking for even browning. Taste and adjust seasonings.
Toss with toasted almonds and bacon pieces and a dab of fresh unsalted butter if desired. Serve hot.