Key limes may be tiny, but the pungent yellow-green orbs carry big flavor. Also known as the Mexican lime or the West Indian lime, the key lime is strong in every dimension—both sweeter and more tart than your standard Persian lime, their juice defined by vanilla notes and complex herbal aromas that come right up to the line of bitterness.
In the summer when key limes come into peak season, I consider them my main squeeze, placing tiny wedges atop tacos and Coronas, and using the potent juice in everything from cocktails to ceviche to a classic key lime pie. But my favorite way to preserve that vanilla-kissed taste is with a key lime curd: The punched up citrus flavor is a perfect foil for the custardy heft of a classic British-style citrus curd. I add kaffir lime leaves as the curd cooks, whose floral aromas lend dimension to a sweet-sour condiment you'll want to use at breakfast, snack time, and dessert.
This curd is delicious spread on breakfast toast, in a layered cake, or dolloped onto pound cake, scones, or ice cream. I also like to use it as a dip for pretzels, sweet apples, or bananas, or slather it between graham crackers. But my favorite way to enjoy it is the simplest of all: straight from the jar with a spoon.