Combine the wine, lemon juice, shallot, garlic and half each salt and pepper in a small saucepan set over medium-high heat. Bring to a boil and simmer until reduced to about 2 tbsp (30 ml). Remove from the heat and cool for 1 minute. Whisk the cold butter into the wine mixture, a few cubes at a time, until well combined; set aside and keep warm.