Tomato Tartine with Green Anchovy Butter

Whenever I wind up with part of a loaf of good sourdough left over from dinner, I like to slice it, put it in a ziplock bag, and keep it in the freezer for toast. This comes in extremely handy during tomato season, when the heirlooms sitting on the countertop have just a few fleeting days of perfect ripeness, and they beg to be sliced and turned into an open-faced tartine. And it’s made all the better when you have a salty, herby, garlic-packed anchovy butter in the refrigerator. This makes