Combine salt, cumin, garlic powder, chili powder and paprika in a bowl. Rub mixture all over the meat. Let stand 20 minutes.
While the steak is sitting, heat 1 tablespoon of olive oil over medium-low heat. Cook onions until softened and they begin to caramelize, about 15 minutes. Stir occasionally. Set aside.
Now begin cooking your steak over medium heat. Cook 4 minutes on each side for medium rare. Cover and let rest for 10 minutes and then, working against the grain, slice into bite size pieces.
While your steak is resting, heat remaining 2 tablespoons olive oil in a small skillet over medium-high heat. Once hot, fry each tortilla one at a time until soft, about 30 seconds per side (you want them soft so that you can roll them). Add more oil if needed. Transfer to plate using a paper towel to separate each tortilla.
Preheat oven to 350 degrees. Spray a baking sheet with non-stick spray.
To assemble the taquitos, place a few pieces of steak on each tortilla, top with pepperjack cheese and sauteed onions. Roll closed. Repeat until all are rolled.
Bake taquitos on prepared baking sheet for 15 - 20 minutes or until the ends start to brown. Remove from oven. Transfer to a serving platter and serve.
If you'd like something to dip these in, guacamole, sour cream and salsa are good choices. Enjoy!