Basic vinaigrette has a fundamental problem: It doesn’t stay together. We sought a way to make oil and vinegar form a long-term bond.

Why this recipe works:
Vinaigrettes often seem a little slipshod—harsh and bristling in one bite, dull and oily in the next. We were determined to nail down a formula for the perfect vinaigrette, one that would consistently yield a homogeneous, harmonious blend of bright vinegar and rich oil in every forkful.
For starters, top-notch ingredients are crucial. Balsamic vinegar works best with more assertive greens. Fruity extra-virgin olive oil is preferred as an all-purpose oil option, while walnut oil is best for nuttier vinaigrettes. As for mixing methods, whisking together the ingredients only gets you so far. A key ingredient—mayonnaise—is necessary to emulsify (bind together) the oil and vinegar for a stabilized, smooth dressing.

• 1 tablespoon wine vinegar (see note)
• 1 1/2 teaspoons very finely minced shallot
• 1/2 teaspoon regular or light mayonnaise
• 1/2 teaspoon Dijon mustard
• 1/8 teaspoon table salt
• Ground black pepper
• 3 tablespoons extra-virgin olive oil

1. Combine vinegar, shallot, mayonnaise, mustard, salt, and pepper to taste in small nonreactive bowl. Whisk until mixture is milky in appearance and no lumps of mayonnaise remain.
2. Place oil in small measuring cup so that it is easy to pour. Whisking constantly, very slowly drizzle oil into vinegar mixture. If pools of oil are gathering on surface as you whisk, stop addition of oil and whisk mixture well to combine, then resume whisking in oil in slow stream. Vinaigrette should be glossy and lightly thickened, with no pools of oil on its surface.

• Red wine, white wine, or champagne vinegar will work in this recipe; however, it is important to use high-quality ingredients. This vinaigrette works with nearly any type of green. For a hint of garlic flavor, rub the inside of the salad bowl with a clove of garlic before adding the lettuce.