I love burgers! (I’ve done a burger recipe in nearly every issue of this magazine for the past 12 years.) However, I also love a tuna melt, so I decided to make a thin tuna steak melt with a pissaladière-inspired onion-and-anchovy topping. This is a fantastic, fancy cousin to tuna melts and patty melts. Serve with a frisée and Bibb lettuce salad with a light vinaigrette.