BLAT

Lay avocado on toast straight from the grill and within a minute it starts to give, the flesh going buttery at the edges where it meets the heat. The first thing the teeth find in a BLAT is that soft, green, faintly nutty layer, which clings to the palate and gives the crisp toast and the snapping bacon a cool, slippery counterpart. Mashed on, the avocado spreads into the crumb and the bread tastes of it. Sliced, it sits in tiles that shift a little when the knife goes through on the diagonal. Mayonnaise survives as a thin film or drops out altogether, since the fruit already brings the richness and the bacon already brings the salt.

Ripeness sets the whole sandwich. A fruit that still resists a thumb tastes of grass and cuts into hard waxy slices that skate off the bacon, and one past its day goes grey at the edges and leaves a bitter, metallic note in every bite. Spread to the crust on the lower slice, a ripe avocado also lines the toast against the tomato, whose salted slices bead for a minute and then sit above it, with cold crackling lettuce over them and the bacon on top, cooked to a snap. A limp rasher vanishes into the avocado and leaves only salt behind.

Salt and acid decide whether the avocado reads as fat or as flavour. A pinch of salt on the slices and a squeeze of lemon, where the cook has a lemon to hand, keep the green bright and put an edge on the buttery flesh, and black pepper cracked over the top gives the first bite a dry heat that carries through the cold lettuce. The squeeze of juice also slows the browning that otherwise starts within minutes of the knife going in.

The first bite runs hot and cold at once. Bacon comes off the grill steaming while the lettuce and tomato come out of the fridge, so one side of the mouth gets salty rendered fat and the other gets watery crunch, with the avocado in the middle taking on whichever temperature the mouth gives it. A BLAT is heavier than a BLT and filling enough to be a whole lunch. The toast softens at the centre after about ten minutes, which makes it a sandwich for the counter or the desk, eaten warm, and a poor traveller in a bag.

In Britain it sits where the BLT already sits: the corner cafe with a grill behind the counter, the sandwich bar with its tray of sliced tomato, the kitchen at home on a weekend. The avocado arrives as an add-on line after the BLT, usually a single word on the chalkboard, and it tends to bring brunch habits with it, a seeded or sourdough loaf standing in for the white sliced. Homes and cafes cut the fruit last, a minute before the sandwich closes, so the slices stay bright green.

Where the A Came From

Bacon, lettuce, tomato and mayonnaise on toast already appear under poultry in American club sandwich recipes around 1903, and dictionaries date the three-letter BLT to roughly 1950 to 1955. The avocado is a later guest. No record names who first slid it into a BLT, a pairing that could happen in any kitchen where a ripe fruit and a grill sat near each other, and the extra letter is simply the spoken shorthand for it.

The name is in print by November 2012, in an "ultimate BLT" recipe that mentions a BLT with avocado is sometimes called a BLAT. That places it as a nickname for an add-in to the standard build, which is how most orders still arrive across the counter: a BLT, then the extra word.

The BLAT gets its own British recipe in September 2018, printed as "the ultimate BLAT sandwich" and built on white bloomer with eight streaky rashers grilled and brushed with sriracha, cherry tomatoes dressed in red wine vinegar, sliced avocado and Little Gem lettuce, with mayonnaise spread thickly on the bread.