Seven layers in a dish, no cooking, and fifteen minutes of assembly. It is a party staple for good reason.

Twelve servings at around 311 calories each.

The beans go down first

Worth stating clearly, because the original method has its first two steps in the wrong order.

As written, step one tells you to spread the sour cream mixture on top of the refried beans, and step two then tells you to spread the beans in the dish. Follow it literally and you are spreading sour cream onto an empty dish.

The correct order is: beans first, then the seasoned sour cream, then guacamole, then the cheeses, then salsa, then lettuce, tomatoes and olives.

Season the sour cream, do not layer it plain

Two and a half cups stirred with two tablespoons of taco seasoning and the juice of half a lime.

Plain sour cream in the middle of this dip is a wasted layer. It contributes coolness and fat and no flavour of its own, and the layers around it are all assertive.

The taco seasoning gives it cumin, chilli and garlic. The lime cuts the richness and stops the layer tasting flat. Together they turn a filler into something that pulls its weight.

Mix it in a separate bowl first, since stirring seasoning into sour cream already spread in a dish is not practical.

Spread each layer to the edges

All the way across, so the layers are visible at the side of a glass dish.

This is presentation as much as anything. A seven layer dip is meant to be seen in cross section, and layers that stop short of the edge look messy through the glass.

It also means every scoop gets all seven components rather than depending on where you dig.

Two cheeses, both shredded

A cup of Monterey Jack and half a cup of cheddar.

Monterey Jack is mild and creamy. Cheddar is sharper and carries more flavour. The larger proportion of Jack keeps the layer from overwhelming the guacamole underneath it.

Neither melts here, since nothing is heated. They are providing texture and salt.

Salsa above the cheese, not below

A sixteen ounce jar of chunky tomato salsa spread over the cheese layer.

The order protects the layers underneath. Salsa is wet, and placed directly on guacamole it would thin it and speed up browning. The cheese acts as a barrier.

Chunky rather than smooth. A thin salsa runs down through the layers and pools at the bottom.

The fresh layers go on last, and late

Shredded lettuce, quartered grape tomatoes and sliced black olives.

These are the components that suffer from sitting. Lettuce wilts against wet salsa within about half an hour, and tomatoes release liquid.

If you are making this ahead, build it through the salsa layer, refrigerate, and add the last three just before it goes out.

Guacamole and browning

Two and a half cups, which is a lot, and it will brown where exposed to air.

Covered by the cheese and salsa above it, the guacamole is largely protected. The edges are where you will see it darken.

Extra lime juice in the guacamole slows it further. If you are making it from scratch rather than buying it, this is worth doing.

Serving

Corn chips, and sturdy ones. This dip is heavy and a thin chip snaps halfway through the layers. <p>Serve it cold, straight from the refrigerator. It keeps two days covered, though the lettuce is best added fresh. ## Making it ahead Build through the salsa layer up to a day in advance and keep it covered in the fridge. Add the lettuce, tomatoes and olives right before serving.

Press cling film directly onto the surface of the salsa rather than covering the dish loosely, which slows any browning at the edges.

The dish to use

Glass, and preferably straight-sided, so the layers show. A trifle bowl or a square glass dish both work. In an opaque dish you lose the entire visual point of the recipe.