1/4 Cup Wine vinegar
2 Tbsp. Dijon mustard
Salt and freshly ground pepper to taste
3/4 Cup Salad oil (canola, safflower or olive oil)
Using a small bowl, whisk together the vinegar, mustard, salt and pepper until salt is dissolved. Add the oil by droplets, whisking until emulsified. If the emulsion breaks, re-whisk before using. The vinaigrette can be held indefinitely in the refrigerator.

Create your own with fresh/dried herbs, minced fresh garlic, honey, freshly grated Parmesan cheese, crumbled Roquefort cheese, olive oil, horseradish or whole grain mustards. Here are a few suggestions:

Add 1 Tsp. Dijon mustard, 1 Tbsp. red wine vinegar or malt vinegar, 1/4 Cup dry vermouth, 1/2 Cup olive oil and few Tsp. of chopped shallots. Salt and pepper to taste.
Add 1 to 2 Tbsp. crumbled Roquefort cheese to 1/2 to 1 Cup vinaigrette.
1 Tbsp. lemon juice, 1 Tbsp. red wine vinegar, 2 to 3 Tsp. Dijon mustard and 7 Tbsp. olive, safflower or canola oil.