3/4 cup sliced peeled carrots
1/2 cup matzoh meal
2 Tbsp olive oil
1 cup chopped onion
1 cup chopped scallions
1 Tbsp lemon juice
1 1/2 lb sole (or other mild fish, such as flounder), cut into cubes
3/4 lb smoked whitefish, flaked off the bone
3/4 tsp salt
1/4 tsp pepper
1 head cabbage
2 garlic cloves, pressed
1/3 cup prepared horseradish
2 Tbsp lemon juice
1 cup mayonnaise
1 Tbsp dill leaves, chopped (optional)
Place the carrots in a saucepan with water to cover, and simmer until beyond tender (and nearly mushy), ~7-10 minutes. Drain, reserving 1/2 cup of the cooking liquid in a large bowl. Add the matzoh meal to the cooking liquid, and place carrots in a food processor.
Heat the olive oil over a medium flame in a heavy skillet. Add the onions, and saute until soft but not browned, ~5 minutes. Add the green onions, and stir 1 minute more. Remove from heat, allow to cool slightly, and add to the carrots in the food processor. Add matzoh meal mixture, and puree until smooth.
Crack 3 of the 4 eggs into a large mixer bowl, and beat until foamy and thickened, ~3-4 minutes. Add the carrot/onion/scallion/matzoh meal mixture, and mix well.
In your now-empty food processor bowl, add the fish, salt and pepper. Pulse until finely chopped, but not pureed. Add the remaining egg, and pulse until just combined. Add this mixture to the vegetable/egg mixture, and stir to combine. Cover and refrigerate until very cold, ~2 hours. Check after an hour -- if the mixture seems like it's too soft to shape, add additional matzoh meal.
After the fish mixture has chilled, set a steamer basket (or multiple steamer baskets if you've got) over simmer water. Peel the leaves off of the cabbage, and use them to line the baskets. Scoop out 1/3 cup of the fish mixture, form into a patty shape of your choosing, and place on the cabbage-lined steamer. Repeat, leaving a bit of space between (the gefilte fish will swell slightly upon steaming). Top with more cabbage. Cover and steam until the gefilte fish is firm and cooked through, ~40 minutes. Remove the cooked patties to a container (along with their cabbage leaves, which will keep them from drying out), and repeat the process with remaining mixture. The fish will be somewhat delicate when you remove it, but will firm upon chilling. Chill cooked gefilte fish in the refrigerator until cold, ~5 hours. Gefilte fish can be made up to two days in advance.
Combine sauce ingredients in a bowl, adjust seasonings to taste, and serve with the gefilte fish.