Roasted Halibut on a Bed of Potatoes

Here’s a recipe from Xavier Franco, a Barcelona chef who truly understands fish. This one is Xavier’s slightly tweaked version of a popular Basque dish that dresses fish with a refrito of fried garlic, chile, good olive oil, and vinegar. The fish comes out delightfully tangy and savory, with the sliced potato layer soaking up all the yummy juices. Because the merluza (hake) called for in the original recipe isn’t easy to find, I substitute halibut. Other firm white-fleshed fis