Why the Bottle Is Not Your Friend

Most of us have a bottle of salad dressing at the back of a cupboard, bought in a moment of optimism, used twice and forgotten. Look at the label and you will usually find rapeseed or sunflower oil, sugar, water and a thickener, with olive oil somewhere near the end of the list. That is not a criticism of the bottle so much as a nudge: a real vinaigrette takes about ninety seconds, uses ingredients you already own, and tastes of something. It also costs a fraction of the price.

The reason most people don't make their own is the belief that a recipe is needed. It isn't. What you need is a ratio, a sharp eye for balance, and the confidence to taste as you go. Once that clicks, you'll stop measuring altogether.

The Ratio That Does the Work

Start with three parts oil to one part vinegar, by volume. Six tablespoons of extra virgin olive oil to two tablespoons of red or white wine vinegar makes enough for a generous bowl of leaves for four people. That is your baseline. Everything after this is adjustment.

A jam jar is the best piece of equipment here. Add your ingredients, screw the lid on, shake hard for twenty seconds. The dressing will turn cloudy and thicken slightly as the oil breaks into tiny droplets. It won't hold forever — vinaigrettes are temporary emulsions and they separate within minutes — but you can always shake again.

• 6 tbsp extra virgin olive oil
• 2 tbsp red or white wine vinegar
• 2 tsp Dijon mustard
• A good pinch of fine sea salt
• A few grinds of black pepper

If you would rather make it in a bowl, add the vinegar, salt and mustard first and whisk them together. Then dribble the oil in a thin stream while whisking constantly. The mustard gives you a head start on the emulsion and buys you a few extra minutes of stability.

Mustard, Salt and Getting It to Hold Together

Mustard is not there purely for flavour. It contains compounds that cling to both oil and water, which is exactly what an emulsion needs. A teaspoon of Dijon per two tablespoons of vinegar is a sensible starting point; a smooth Dijon behaves better than a coarse wholegrain, though the latter is perfectly nice for robust salads.

Salt matters more than most people expect. Salt dissolves in vinegar and water, not in oil, so add it before the oil goes in or it will simply sit at the bottom of the jar. As a rough guide, a quarter teaspoon of fine sea salt per six tablespoons of oil is right for most palates, but err on the side of generosity — an under-seasoned dressing tastes thin and greasy instead of bright.

And taste the dressing on a leaf, not from a spoon. Oil coats the tongue and mutes perception, so a spoonful will always taste weaker than the same dressing tossed through salad. Dip a piece of the actual leaf you plan to serve, shake it, eat it, then decide.

Tasting and Adjusting: The Four Dials

Think of your vinaigrette as having four dials: salt, acid, sweetness and fat. Here is how to read them.

• Dull, flat, tastes of nothing much: add salt first, taste again, then add more vinegar. Most disappointing dressings are simply under-seasoned.
• Sharp enough to make you wince: add more oil, or a small pinch of caster sugar or a little honey. A teaspoon of water also softens acidity without adding sweetness.
• Slippery and cloying in the mouth: add more vinegar, or a squeeze of lemon juice, which brings a sharper, brighter kind of acidity.
• Raw garlic burning at the back of your throat: use less, or steep a halved clove in the vinegar for ten minutes and remove it before dressing.

Write nothing down. Next time, you'll taste it and know.

Matching the Vinaigrette to the Salad

The same dressing will not suit everything, so adjust the ratio towards the dish.

• Soft, delicate leaves — butterhead, lamb's lettuce, young spinach. Loosen the dressing with lemon juice instead of some of the vinegar, go easy on mustard, and dress the leaves at the very last moment.
• Peppery and bitter leaves — rocket, watercress, chicory, radicchio. These can take a punchier vinaigrette with a strong mustard and a peppery olive oil.
• Tomatoes. Push the acid up, skip the mustard if you like, and add a pinch of sugar if the tomatoes are pale and supermarket-ripe. Drizzle rather than toss.
• Pulses and grains — chickpeas, lentils, butter beans, farro. Dress them while still warm so they drink it in, and be generous; they soak up far more than leaves do.
• Roast vegetables. A sherry or balsamic vinegar works beautifully here. Drizzle over the tray the moment it comes out of the oven.

Choosing the Oil, and Keeping What Is Left

Dressings are where you taste olive oil raw, so use an extra virgin you would happily dip bread into. The blended, milder oils sold for everyday cooking belong in the roasting tin, not the jar. A peppery oil with a bit of a kick suits bitter leaves and grilled vegetables; a softer, rounder oil from Greece or Spain is lovely with tomatoes, beans and grains. Avoid anything labelled "light" — that usually means refined for heat, with most of the character stripped out.

Leftover vinaigrette keeps in a sealed jar in the fridge for about five days. Extra virgin olive oil will thicken and go cloudy when cold, which is normal and a decent sign of the real thing. Take it out twenty minutes before you need it, or stand the jar in a bowl of warm water and shake. Any garlic or fresh herbs in the mix will fade after a couple of days, so add those fresh each time if you can. The oil and vinegar themselves will keep for weeks.