Which fish you choose is up to you as long as it's a firm white fish like halibut, mahi-mahi, barramundi or cod. They are all great here!
This recipe can be scaled up and down to your liking here it serves 2.
Be sure to use waxy potatoes, they usually have yellow skin, and avoid russets which are starchier.
2 small filets of halibut (or similar fish) per person, about 6 ounces of fish per person
2 medium waxy potatoes
large sauté pan with a lid (in a pinch use a sheet tray as the lid)
a small handful of grape tomatoes, sliced in half
5 black olives, pitted and sliced in half— I like gaetas here but any olive you love is great
1 clove of garlic, peeled
Peel the shallot. Clean and dry the potatoes. Carefully slice the potatoes with a mandolin. Carefully slice the shallot with the mandolin. If you don't have one use a sharp knife and slice everything as thinly as possible.
Heat 2 Tablespoon of olive oil in a large sauté pan over medium heat. Add the potatoes and shallot making sure they are in as much of an even layer as possible. Sprinkle with a teaspoon of salt and cover. Cook, pushing under the potatoes and shallots with a spatula, about every 3 minutes or so, so that nothing burns but don't stir just flip and scrape. Making sure that everything remains as even in layer as possible.There will be a bit of fond (the caramelized bit at the bottom of your pan) incorporate that and if everything is sticking add a bit of water— about 2 Tablespoons (or if you have some wine or broth you can add that instead). Continue cooking until the potatoes are cooked through and the shallot has caramelized— about 10 minutes.
Take the shallots and potatoes out of the pan and place them on a plate. Cover the plate with foil.
Pat the fish dry and season with salt. Heat 1 Tablespoon of oil, you can use the same pan you used for the fish, over medium high heat. Once the oil is shimmering add the fish and cook it with out touching it for 3-4 minutes. The edges of the fish will become opaque and then it will be time to flip it using a spatula. Cook for another 3 minutes and remove from heat. Squeeze some lemon over the fish.
In the same pan, heat a glug of olive oil and add the sliced tomatoes. Sauté them over medium heat until they are slightly cooked, about 2 minutes. Microplane half a clove the garlic over the tomatoes and continue cooking for another minute. Add the olives and toss a few times. Remove from heat. Serve the tomatoes and olives over the fish .