This is the first sauce recipe I ever learned in the kitchen. Even though I hadn't made it in a long time I still managed to make this from memory. Having this recipe memorized can get you out of some tough spots. It's flexible and contains only common ingredients in your kitchen. You can coat just about any food with this sauce, including pasta, vegetables, and seafood.
The only thing that I am particular about with this recipe is the reduction of the wine. You want to fully evaporate all the alcohol from the base of the sauce before you add the butter. To make sure you reduce all the alcohol from the sauce, watch the bubbles at the bottom of the pan. When you add the wine there should be an instantaneous cloud of evaporated alcohol and water rising from the pan. (If there isn't don't worry, your sauce will be fine.) After the cloud of vapor, there will be bubbles forming at the bottom of your pan. Observe the size of them. They should be very large at first. Once they get to be about 1/2 to 1/4 the size of the biggest bubbles you observe, your alcohol is evaporated.
To make this a less arduous task, you can also look at how much liquid is left in the pan. If you add a cup of wine to a cup of other ingredients, there should be about 1 and 1/4 to 1 and 1/2 cups of total sauce left once the alcohol is gone. In other words, the amount of wine you added should be reduced by about 1/2.
The added acid (lemon juice, vinegar etc.) is entirely optional. In fact, I only use it when I am adding this sauce to seafood, but that is just me.
Oh, and one more thing. Chop the onion as finely as you can. The finer the onion texture the creamier the sauce will be.
White Wine Sauce:
1 to 2 tablespoons plus 1/4 cup unsalted butter
1/4 cup finely chopped white onion
1 scant teaspoon lemon juice, white vinegar, or white flavored vinegar (optional)
1 cup dry white wine
1 stick of butter, unsalted
1. Melt the 1 to 2 tablespoons of butter in a saucepan over medium heat.
2. Increase the heat to medium-high and add the onion.
3. When the onion becomes translucent, add the wine and the optional lemon juice/acid. Increase the heat to high.
4. Reduce until the alcohol is evaporated.
5. Reduce heat to medium and add the stick of butter. Whisk in the butter as it melts until it is completely mixed into the sauce.
6. Reduce heat to low and wait to toss with the other food.