This is the best fish recipe I've ever made! It's so flavorful, thanks to the brininess of the olives and capers combined with the garlic and red pepper. The recipe is very flexible: I've made it with both fresh and frozen fish (swordfish, halibut, and cod), different types of green olives (including standard pimento-stuffed Manzanillas), and both red and yellow onions; it's always delicious. This dish is simple to make and, with the exception of the fish itself (if I want to use fresh rather than frozen), requires only ingredients I usually have on hand. Despite its comparative simplicity, this dish makes a great "company" dinner. I make it exactly as written except that I don't bother to peel the potatoes (cutting down prep time), and if I'm making only a single serving and don't want to open a whole can of plum tomatoes, I substitute fresh cherry tomatoes (halved).