It's a relatively expensive white fish, low in mercury, with a pleasant neutral taste. Stuffed with spinach, it's a healthy meal perfect for holidays or any large family gathering.
Extra filling can be used to make individual spinach souffles, an excellent side dish.
Step 1: Ingredients
3 pounds fillet of sole
~1/4 cup chopped mushrooms (optional)
2 bunches spinach (large leaves, not baby spinach)
handful walnuts (~3 heaping tablespoons)
handful peeled garlic (3-15 cloves, depending on your taste for garlic!)
1/3 pound feta cheese
salt & pepper to taste
Optional, for souffles:
Step 2: Saute Spinach and Mushrooms
When the mushrooms are cooked through, add the spinach1 in handfuls. Stir, and as the spinach wilts add more. When all your spinach is cooked through, remove pot from heat and proceed with the next step.
1 Be sure to wash spinach carefully! It can be loaded with dirt. It's best to fill a bowl with water, and swish handfuls of spinach around while fully submerged. Set the washed spinach in a colander to dry, and change the water between batches if it gets muddy.
Step 3: Puree Stuffing
If you don't have one, finely mince all these ingredients by hand - it's too dry for a blender.
Pulse the garlic and walnuts in the food processor, scraping down the bowl as necessary.
Drain the spinach, and add to the mix along with the mushrooms. Pulse between additions, and add more spinach when you've created space.
Now add the feta, and any seasonings you like (nutmeg, black pepper) and pulse again.
You should have a nice thick pesto-like sauce that smells strongly of garlic. Scrape it out of the food processor into a bowl for ease in loading up your fish fillets.
1 You can also use this as an excuse to finally buy a decent food processor. It's a basic multi-purpose kitchen implement you'll find weird additional uses for - we use ours on an almost daily basis for pestos, hummous, shredded veggies for salads, etc. I recommend the Cuisinart 7-cup food processor: it's just the right size, under $100 (you can often find it on sale even cheaper), does everything, and doesn't have additional moving parts to clean like the 11-cup version.
Step 4: Stuff and Roll
You'll want a space (preferably a plate or bowl, but it could be the end of your pan) to hold your fillets, and the bowl of filling with a spoon. Even better, get a helper to scoop the filling for you to prevent cross-contamination from your fishy fingers. Try not to touch the spoon to the fish, again to prevent cross-contamination and make cleanup easier.
Dab a scoop of spinach filling about 1/3 of the way along your fillets, and begin rolling around the spinach from the short end. It doesn't really matter whether this is the head or tail end - experiment with both to see if you have a preference. I didn't notice a difference.
Don't worry if a bit of the spinach mix squeezes out the sides - it will still look good. This doesn't have to look perfect.
Set each rolled fillet aside, lining them up in the pan as you go.
Step 5: Top and Bake
Bake in 350F oven, uncovered, until just cooked through1. The accumulated liquid in the bottom of the pan will begin to bubble and sizzle, indicating the fish is done. Overcooking can dry the fish out, so keep an eye out for dryness.
You can also check via thermometer! Aim for an internal temperature of about 140F. (Thanks to fegundez1 for the suggestion via comments.)
1 My 9x14 pan took roughly 20 minutes, but there were other things in the oven - your mileage may vary. Check the picture below and watch for the juices sizzling to indicate doneness.
Step 6: Bonus Spinach Souffles
Just add a tablespoon or two of breadcrumbs, and a pinch of baking powder. If there's lots of filling left you can add another egg to give it more lift.
Mix together, dump into greased ramekins, and slip into the oven alongside the fish.
These will cook quickly, so keep an eye out - they're done when slightly golden at the top, and pulling away from the container's edge.
Remove and cool. They'll deflate a bit, but still taste good. Serve in the ramekins, or flip out and eat directly.
Step 7: Serving and Storage
It goes well with many dishes, but I'd particularly recommend a rice pilaf and some green beans and roasted sweet potatoes.
Surprisingly, the fish also stores quite well. I placed the fish in a pyrex bowl and covered it with the juices from the pan. The next day it was moist and reheated beautifully with a very brief stint in the microwave - the perfect leftover lunch. The flavors had mingled well, and everything remained perfectly moist.
Give it a shot, and tell me know how you like it. I'm particularly interested in any modifications - let me know so I can try them out next time!