Put tuna in a food processor and pulse to break up the fish. With the machine running, add the lemon juice, soy sauce and balsamic vinegar. Add butter and blend until smooth, then scrape down the sides, season to taste with salt and pepper and blend again. Check the seasoning, then add the heavy cream and pulse to blend. Be careful not to overblend once the cream is added or the mixture may break. Serve at room temperature, or cover and refrigerate. If refrigerated, return the spuma to room temperature before serving. |