Grill steak until medium rare. Remove from grill and let rest for 10 minutes.
Place parsley, spinach and cilantro in food processor or blender container. Add garlic powder, salt and pepper. Cover and pulse until the spinach is finely chopped. Add the olive oil and vinegar. Process just till blended. It should still have a few recognizable bits in it!
Clean and slice bell peppers into thin strips.
Slice onion into thin strips.
Warm tortillas by wrapping in foil, then placing in a 350 degree oven for 15 minutes.
You can also use an un-greased griddle to warm tortillas. Heat the griddle over high heat, then place tortillas onto the griddle, one at a time, flipping after 20 seconds. Set warmed tortillas on a plate and cover loosely with foil, or with one unheated tortilla in order to keep them warm as you finish each one.
After steak has rested for 10 minutes, slice thinly on the bias.
Spread each tortilla evenly with Chimichurri Sauce, leaving a 1 inch border around edge.
Top with salad greens, bell pepper slices, onion slices and beef slices, taking care to leave the bottom third of the tortilla empty and also 2 inches on both the right and left side of the tortilla.
Fold the bottom third of the tortilla up over the fillings.
Now fold the left side of the tortilla across the the middle of the tortilla, then do the same for the right side, making sure that the edges overlap. Use a toothpick to hold the wrap closed while you assemble the remaining tortillas.