Ingredients

• 1 ¼ pounds mahi-mahi, swordfish or halibut steaks, about 3/4 inch thick

• ¼ teaspoon sea salt

• ¼ teaspoon ground pepper

• 6 canned plum tomatoes, drained and very coarsely chopped

• 2 stalks celery, diced

• ½ medium red onion, halved and sliced

• 1 cup green olives, pitted

• ¼ cup capers, preferably salt-packed, well rinsed, plus more for garnish

• ¼ cup extra-virgin olive oil

• 1 clove garlic, chopped

• ⅛ teaspoon crushed red pepper, or to taste

• 1 ½ cups thinly sliced peeled yellow-fleshed potatoes

• ¼ cup chopped flat-leaf parsley