Juice from 1 Meyer lemon or other fresh lemon, approximately 4 tablespoons
extra virgin olive oil, approximately 3/4 cup
sea salt and freshly ground black pepper
Add the Meyer lemon juice and a pinch of salt and pepper to a small bowl. Then slowly add the olive oil, whisking as it is added. The final amount of oil will depend on the actual amount of juice from the lemon and your personal taste. Generally you want to have a ratio of 1 part acid (lemon juice, vinegar, etc) to 3 parts oil. I prefer a vinaigrette with is closer to 2 or 2 1/2 parts oil, but again make it according to your preference. Taste and adjust the oil or lemon juice.
To make a basic red wine vinaigrette just use red wine vinegar or perhaps a mixture of red wine vinegar and balsamic vinegar and then add the oil in the same ratio as above. You can modify the vinaigrette, to your taste, by adding such things as a teaspoon of Dijon mustard, some minced garlic, finely chopped fresh herbs, or some dried herbs such as oregano, before whisking in the oil.