homemade lemon caper mayonnaise on grilled flounder

The temperature climbed almost to 90 today and, even after a complete shave-down last week, poor little Hugo could barely muster the energy to walk around the block. It’s the kind of day that requires grilling and cold drinks. In our case, fish was most definitely on the grill (Tuesday is the csf pick-up day), and cold drinks came in the form of an already open bottle of prosecco that needed finishing. After watching a very helpful video on filleting flounder on How to Heroes, I set out filleting our 6 (gasp, sputter) whole flounder. I was kind of panicking, thinking we’d be eating flounder for the rest of eternity, but flat fish and all, they really didn’t yield all that much fish, and dredged in homemade lemon caper mayo, we polished off 3 in one sitting.
Which brings me to today’s recipe, inspired by this month’s Food and Wine, which has page after page of really tasty simple looking grilling ideas. The recipe that caught my eye was for grilled trout bathed in a dressed up mayo and then grilled and served with more mayo on the side. Food and Wine keeps it extra simple, just doctoring up bought mayo, but since the recipe already required a blender, I figured it would be worth the extra 30 seconds to make mayo from scratch. Homemade mayo is such an awesome treat – so creamy and made with a good olive oil, so so much more flavorful than its bought counter-part. And, best of all, it’s easy enough to make that once you try it you’ll never go back to store bought. 

Apart from starting with a homemade base, I kept the recipe pretty close to the original – lemon juice and zest, some shallots, parsley, and capers. So delicious. This was perfect on the flounder and would be magic on any kind of seafood. I like it because it’s not overly caper-y, just zingy enough so that the flavor of the olive oil and the other ingredients still come through. Lucky for us, the recipe made more than enough for our flounder, and we’re already planning steak sandwiches with the leftovers for tomorrow. Makes about 1 to 1½ cups, enough for 16 small flounder fillets (or more) to serve 4-6 people.

For the Lemon Caper Mayonnaise
3 egg yolks
½ cup extra virgin olive oil
1 small shallot, finely chopped
2 tbsp drained capers
2 tbsp chopped parsley
Zest of half a lemon
2 tbsp lemon juice (about half a lemon)
Salt and pepper

Make the Mayonnaise
Place the egg yolks in the base of a blender and top with a little salt and pepper. With the blender running, very very slowly drizzle in the olive oil. You may want to put the olive oil in a pitcher or measuring cup with a spout to make it easier to pour slowly. The egg-oil mixture will emulsify (thicken) as you pour. Once all the oil is added, stop the blender and add the remaining ingredients. Pulse a few times, scraping down the sides of the blender in between, until the mayonnaise is well combined – it should still have some texture. (You can also do this all by hand using a metal bowl and a whisk – just make sure to add the oil very slowly and very finely chop the other ingredients.) Transfer to a small bowl, taste for seasoning and adjust as needed, and refrigerate until ready to use. 

For the Grilled Flounder
8-16 skinless flounder fillets, depending on size
One recipe lemon caper mayonnaise (see above)
Salt and pepper
Lemon wedges for garnish

Grill the Flounder
Preheat your grill to medium-high. Generously rub the filets with the mayonnaise, reserving at least half for serving. Sprinkle lightly with salt and pepper. Lay the filets in a grill basket* or on a sheet of tin-foil and grill 1-3 minutes per side, depending on the size of your filets. The fish will shrink slightly as it cooks and should be firm to the touch and very slightly browned. Serve immediately with lemon wedges and the remaining mayonnaise. 
* I find flounder is too thin and delicate to grill without the added support of a basket, which allows the fish to still get some smokiness and charring from the grill, without the risk of falling through the grates. If you don’t already have a grill basket though, by all means just use a sheet of tin foil.

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