Although not quick and simple, the following makes an incredible first course, if I say so myself. It's something I came up with last summer, as a way to use up the surplus zucchini.
If you've got lots of patience, this can be done with baby zukes. But small/medium ones really make more sense.
SARDINE STUFFED ZUCCHINI
2 medium zucchini
2 can skinless/boneless sardines
salt & pepper
1 tbls minced red onion
Squirt of Dijon mustard
Thinly sliced Fontina cheese
Hot sauce spiked egg wash
Oil for frying
Red wine vinegar reduction (1 cup vinegar & 2 tbls sugar, cooked down until syrupy)
Shaved Parmegiano Reggiano
Using a mandoline or very sharp knife, slice zucchini lengthwise, about 1/8th inch thick, keeping each two slices matched to each other. Sprinkle with salt. Sandwich between paper towels. Set aside to let some of the moisture drain.
Make filling: Mash sardines with salt, pepper, onion, mustard, and just enough mayo to bind mixture.
Sprinkle slices with pepper. Using matched pairs of zucchini slices, put a layer of sardines on one side of each pair. Top with Fontina. Do not let either the sardines or cheese overlap the edges. Cover with second zucchini slice.
Dip each sandwich first in flour, then egg wash, then panko crumbs mixed with salt, pepper, and oregano. Sauté in oil until browned on each side and cheese is melted.
Put a layer of caponata on serving plate, slightly longer and wider than the zucchini sandwich. Top with zucchini sandwich. Squiggle vinegar reduction over zucchini. Garnish with slivers of Parmegiano Reggiano.