Sweat shallots in a small pan over medium heat in a little vegetable oil until translucent. Add white wine, pinch of salt, thyme, bay leaf and peppercorns. Allow wine to reduce by half, add beer and reduce slightly.

Meanwhile, warm cream in a separate pan over low heat. Slowly whisk cream into wine reduction and gently bring to a simmer.

In a small bowl, combine cornstarch and water with a whisk to make a slurry. Slowly stir a small amount of slurry into the cream and wine mixture to thicken it until it coats the back of a spoon. Bring the mixture back to a simmer and then remove from heat.

Whisk in cubed butter in small batches, waiting for previous addition of butter to melt and incorporate before the next batch is added. When all of the butter has been incorporated, whisk in lemon juice and season with salt to taste. Do not overheat or boil the sauce, as this will cause it to break. Strain sauce through a fine mesh sieve or cheesecloth, and keep warm until needed.