1 1/2 teaspoons chili powder
In a small bowl, combine the chili powder, cumin, coriander, salt, and pepper.
Rub the spice mixture over all sides of the flank steak, place it in the bottom of the slow cooker, and add the soy sauce.
Top the flank steak with the jalapeno, garlic, 3 of the peppers, and onion. There's no need to add any water or other liquid.
Cook on high for 5 to 6 hours or on low for 8 to 9 hours, or until steak can easily be shredded with two forks.
Near the end of cooking time, heat a small amount of oil in a medium saute pan and cook the 2 remaining sliced peppers until softened, but still retaining their bright color.
Thoroughly drain the meat and peppers, saving the juiced. Shred the meat, and serve with the fajita fixings of your choice.
Recommended accompaniments: Whole wheat flour Tortillas, freshly grated Monterey Jack cheese, sliced avocado, fresh cilantro, lime wedges, fresh chopped lettuce, sour cream and/or diced jalapenos.