Kale and Mushroom Stuffed Flank Steak

I was inspired by this recipe: http://mypanera.panerabread.com/recipes/recipe/spinach-and-wild-mushrooms-stuffed-flank-steak-spirals/

This was enough to feed 8 people.

Spice rub:

• 4 t paprika
• 1 T black pepper
• 1 t chili powder
• 4 t salt
• 2 t sugar
• 1 t coriander (ground)
• 1 t thyme
• 1/2 t garlic salt (I didn't have any garlic powder)
• 1/2 t dried minced onion (again, I didn't have any powder)

about 5 lb. of flank steak (it was three steaks)
1/4 cup olive oil, divided
1 onion, finely chopped
4 (or more) cloves of garlic, minced
about 9 oz mushrooms, sliced
2 bunches of kale, spines removed and chopped
about half a bunch of fresh parsley
2 red bell peppers, trimmed and sliced into thin sticks

Combine the spice rub in a small bowl.
Warm half of the olive oil in the biggest skillet, wok, or dutch oven you have.
Saute the onion and garlic a little.  Add the mushrooms and continue to cook.
Add the kale a little at a time, so it has time to cook down, so there is room to add more to the pan.  (I added it as I chopped it, a few leaves at a time.)
Add the parsley and about 4 teaspoons of the spice rub.  Remove from heat.
Butterfly and/or pound the meat until it is evenly between 1/4" and 1/2" thick.
Cut a lot of pieces of kitchen string, to tie around the meat once it's rolled.  (At least 5 per piece of meat.)
Rub with the remaining oil, and then the spice rub.
Make sure the meat grain is running side-to-side.
Arrange the bell pepper pieces horizontally on the bottom 2/3 of the meat.
Cover most of the meat with the kale mixture, leaving about a 1 inch border on the top edge.
Roll the meat up, away from you, and tie with the string.
(I did all of this the day before, wrapped it all in plastic wrap, and refrigerated it over night.)
Heat the oven to 500F.
Line a baking sheet (with sides) or baking dish with aluminum foil, and arrange so the pieces of meat are not touching.
Roast 8-10 minutes, until beginning to brown.
Reduce heat to 350, and continue to roast 20-25 minutes, until internal temperature is 130F.
Remove from oven, and let rest for 15 minutes.
Cut into 2" slices, removing the string as you go.