Slice flank steak thin as for scallopines or bracioles, and slices pounded thinner- to at least 2 by 4 inches (3 by 4 or so is ideal); three pounds of meat should yield at least 30 slices.
Prepare stuffing (saute).
Heat about 1/4 cup olive oil in heavy based pan, and saute the onion, half the garlic, and red chile, until onion is translucent.
Add hazelnuts (or pine nuts)- if using ground hazelnuts, saute until nuts release oils and thin out.
Add minced mushroom stems and cook until stems have released juices, and mixture darkens and seems to dry out.
Add tomato pulp and juices, currants/raisins (if using) and the 1/2 cup red wine, and continue, until alcohol cooks out.
Remove from heat and cool slightly.
Then add grated cheese, anchovies, and herbs and mix well.
Taste for salt and pepper and add as needed.
Add the egg and mix again, and then add about 1/2 to 3/4 cup of the bread crumbs- mixture should hold together well.
Taste again for salt and pepper and add as needed/desired (I use about 1 tbs black pepper; salt depends on anchovies and cheese, which are salty).
Prepare meat speidinis.
Spread stuffing on meat slices and roll tightly, like a jelly roll.
Or, if slices are large enough, you can place stuffing in center and fold over each side to make a neat packet.
Secure meat on skewers, speidini style: Use two skewers; one securing each end of meat packet, and running parallel to each other, so that you will end up with a two-skewer kebob, with the packets centered between.
This method allows for better handling and cooking of the kebobs, since packets can be turned, basted, and grilled much more efficiently.
Alternate meat with sage leaves, if using.
Prepare mushroom speidinis by filling each cap with stuffing, and then making a sandwich with two caps top to top.
If using the sage leaves, they can be placed between the sandwiched mushrooms for extra flavor.
Skewer using the same two skewer method as for the meat speidinis, for secure easy handling.
Marinate the speidini kebobs in a mixture of olive oil, the other half of the garlic, and red wine.
Marinade can be adjusted to taste, by adding more herbs or seasonings- depending on the packet or stuffing used for the speidinis.
I use a roasting pan so the speidinis lie flat in the marinade.
Turn often enough so both sides marinate.
Marinating time is flexible- at least one hour, but can marinate overnight, if covered and refrigerated.
Just prior to cooking the speidinis, remove from marinade, and coat lightly in the remaining bread crumbs on both sides.
Grill or broil the speidinis, turning one; about 6 minutes for each side, or to taste.
Alternatively, speidinis can be cooked in a hot oven (475 F preheated); about 10 minutes for each side (on a baking sheet or roasting pan).
Variations: stuffing recipe here can be used to fill rolled eggplant slices (slice length-wise and parboil/steam/quick saute before rolling), or pepper rolls (roast peppers and remove as much skin as possible, then cut to speidini size pieces).
Other meats can be used with various stuffings; a simple sauted and herbed onion dressing is also very nice, and quite traditional as well.