Salad dressing is built from two core elements: a fat (usually oil) and an acid (usually vinegar or citrus juice). Everything else, from mustard to mayonnaise to sugar, builds on that foundation. The specific ingredients vary widely depending on whether you’re making a light vinaigrette, a creamy ranch, or buying a bottle off the shelf, but that fat-plus-acid backbone stays the same.
The Two Ingredients in Every Dressing
Oil provides the body and richness of a dressing, while acid gives it brightness and tang. The classic vinaigrette ratio is 3 parts oil to 1 part vinegar. Some people prefer a sharper dressing and drop to 2 parts oil, but that 3-to-1 standard is where most recipes start.
The type of oil matters. Extra virgin olive oil is the most popular choice for vinaigrettes because of its fruity, peppery flavor. Neutral oils like canola or grapeseed let other flavors dominate. Specialty oils like walnut, sesame, or flaxseed add distinctive character but tend to be used in smaller amounts or blended with a milder oil.
On the acid side, you have two main categories. Vinegars, including red wine, white wine, balsamic, sherry, apple cider, and rice vinegar, each bring a different flavor profile. Citrus juices, particularly lemon and lime, are the other common choice. Vinegar typically has a pH around 4.5, while lime juice is closer to 2.2, making citrus significantly more tart drop for drop. That difference means you’ll generally use less citrus juice than you would vinegar to reach the same level of acidity.
What Holds It All Together
Oil and vinegar naturally separate. To get a dressing that stays blended, you need an emulsifier, something that helps oil and water-based liquids mix. In home kitchens, the most common emulsifiers are mustard and egg yolk. A teaspoon or two of Dijon mustard in a vinaigrette does double duty: it adds flavor and keeps the dressing from splitting in the bowl. Egg yolk is the powerhouse emulsifier in mayonnaise-based dressings and in classic Caesar.
Honey, tahini, and miso paste also help stabilize dressings while contributing flavor. In commercial products, manufacturers use ingredients like lecithin, modified food starch, and other stabilizers to keep bottles shelf-stable for months.
Vinaigrettes vs. Creamy Dressings
Vinaigrettes are the simplest category. Oil, acid, salt, pepper, and maybe mustard or a minced shallot. A classic French vinaigrette might add chopped hard-boiled egg, capers, cornichons, and fresh tarragon to that base. Italian dressings fold in dried oregano, garlic, and sometimes a pinch of sugar. The texture is thin and pourable.
Creamy dressings start from a thicker base. Traditional ranch is built on mayonnaise and buttermilk, seasoned with garlic, onion, dill, and chives. Caesar dressing combines egg yolk, oil, lemon juice, garlic, anchovies, and parmesan. Blue cheese dressing uses a mayonnaise or sour cream base with crumbled cheese stirred in. Greek yogurt has become a popular substitute for mayonnaise in lighter versions of all these dressings, providing the same thick, creamy texture with less fat.
Thousand Island and Russian dressings add ketchup or chili sauce to a mayonnaise base, along with sweet pickle relish and other mix-ins. The pink color comes from the tomato-based ingredient, not from any artificial dye.
What’s Actually in the Bottle
Commercial dressings follow the same basic formula but add several categories of ingredients you won’t find in a homemade version. The U.S. FDA has a specific legal definition for products labeled “salad dressing”: they must contain at least 30 percent vegetable oil by weight, an acidifying ingredient (vinegar, lemon juice, or lime juice), an egg yolk component, and a starchy paste made from ingredients like food starch or wheat flour. That starchy paste is what distinguishes the FDA’s “salad dressing” from “mayonnaise” in regulatory terms.
Beyond those required ingredients, bottled dressings commonly include preservatives to prevent spoilage and maintain color. Potassium sorbate and sodium benzoate inhibit mold and bacterial growth. EDTA (listed on labels as calcium disodium EDTA) preserves color and flavor. Antioxidants like BHA, BHT, and tocopherols slow the oil from going rancid.
Sugar is another major addition. Commercial dressings often contain more sugar than you’d expect. Some French dressings contain around 16 grams of sugar per serving, which is nearly twice the sugar concentration found in cola. Even dressings that don’t taste sweet, like many ranch and Italian varieties, frequently list sugar or high-fructose corn syrup in the first several ingredients. Sodium levels also run high in most commercial options, often 200 to 400 milligrams per two-tablespoon serving.
Flavor Add-Ins That Change Everything
The fat and acid are the canvas. The add-ins are where dressings get their identity. Salt is the single most important seasoning, pulling flavors together the way it does in any dish. After that, the possibilities branch out quickly.
- Aromatics: Minced shallot, garlic (raw, roasted, or powdered), and fresh or dried herbs like basil, dill, oregano, cilantro, and tarragon.
- Sweeteners: Honey, maple syrup, agave, or plain sugar to balance acidity. A small amount can soften a sharp vinaigrette without making it taste sweet.
- Umami boosters: Anchovy paste, parmesan, soy sauce, miso, and fish sauce all add depth. Caesar dressing relies on anchovies and parmesan for that savory punch.
- Heat: Crushed red pepper, sriracha, gochujang, or fresh chilies.
- Creamy elements: Tahini, avocado, nut butters, or coconut cream for dairy-free richness.
Making Your Own vs. Buying
A basic vinaigrette takes about two minutes to make. Whisk together six tablespoons of olive oil, two tablespoons of vinegar, a teaspoon of mustard, and salt and pepper. That yields about half a cup. It will keep in the fridge for a week or so, though you’ll need to shake or whisk it again before each use since homemade dressings lack the industrial stabilizers that keep bottled versions emulsified.
The practical trade-off is shelf life. Homemade dressings, especially those with fresh garlic, herbs, or dairy, last days to a couple of weeks refrigerated. Commercial dressings stay stable for months unopened and weeks after opening because of their preservatives, stabilizers, and processing methods. If you go through dressing slowly, a bottle makes more sense. If you eat salads regularly, making your own gives you control over sugar, sodium, and oil quality while costing a fraction of the price.