Ripe, sun-warmed, in-season tomatoes are a critical component to a perfect BLT. So is bread that is toasted on one side only. (The bacon? Negotiable.)

A properly put-together BLT is the Bruce Lee of sandwiches. It’s lean and light and full of fight.

Plus, during the height of heirloom tomato season – happening right now in gardens and at farmers markets around Monterey County – this black-belt combination of tomato, onion, mayo, bacon, bread and lettuce provides an excellent way to show off the reds, oranges and goldens of this late summer staple.

The BLT is a masterpiece of a sandwich, and a masterclass in all-around sandwich-ology, in part because pulling off a perfect one is not easy. There are some challenges inherent to a BLT, but a clever cook can find the way past these pitfalls.

For example, the watery combination of tomato and mayo threatens the integrity of the bread. But this combination is non-negotiable – that the tomato must be in contact with the mayo is one of the few hard and fast rules of the BLT. It’s the backbone of the flavor combination, more important than the bacon itself. In fact, it’s precisely for this reason that vegetarians and other non-bacon eaters can enjoy what I consider a true BLT experience. Just insert your favorite bacon substitute into the equation and karate-chop that sucker in half – diagonally, corner to corner.

You won’t miss a step with your fakin’ bacon, but kid you not: If you don’t manage that tomato-mayo situation properly, your BLT will self-destruct in about 25 seconds.

The obvious solution to this challenge is to toast the bread, right? The resulting browned, crusted finish that develops on the slices can withstand the dual onslaught of tomato and mayo and keep itself together long enough to pack into a lunchbox.

But there is a downside to toasting the bread of a sandwich as delectable as this one. You can become so entranced by the flavor that you eat the sandwich too quickly and the sharp edges of the heat-hardened crust cut into your mouth behind your teeth, in a manner that is most unsatisfying.

It seems wrong that we must choose between bread that has reverted back to dough phase due to contact with the tomato and mayo, or risking the roofs of our mouths on the jagged crust as we chomp, eyes rolled back in our heads like frenzied sharks.

The answer, one of the most brilliant culinary tricks ever, comes from a farmer friend. I use it on nearly every sandwich I make for myself, BLT and non-BLT. It goes like this.

Place two pieces of bread, pressed together as if in a sandwich, in a toaster oven or extra-wide toaster. Set toaster to medium. When the bell dings, each piece of bread will have a toasted side and a not toasted side – the toasted sides being the two outer sides of the double slice of bread, with the non-toasted sides facing each other inward.

Now, prepare your BLT.

Lay the two slices of half-toasted bread on a plate or cutting board, with both toasted sides facing up. Slather mayo on the toasted sides of both. Lay some sliced tomatoes on one mayo’d face, and thin-sliced onions on the other.

Lay the bacon strips (or a substitute) over the tomatoes, and layer with lettuce. Place the onion/mayo piece on top of the lettuce, so that the toasted faces are now lathered with mayo and facing inward, while the soft, untoasted sides of each slice face outward.

And that, in short, is the half-toasted bread technique.

When you first bite into a sandwich made with half-toasted bread, everything is soft. Your teeth will soon reach the mayo’d, toasted faces. Bite through, and into the sandwich. You’ve just successfully avoided both soggy bread and the unpleasant impacts of sharp crust.

Once you try it, you may never make a sandwich the old way again. This technique works with sandwiches besides the beloved BLT too, from peanut butter and jelly to tuna fish to egg salad, etc. But let’s be real – heirloom tomato season is peak time for a BLT. And with this trick under your belt, you’ll be happily eating sandwiches all season long.