In a bowl, whisk together all marinade ingredients: olive oil, soy sauce, lime juice, minced garlic, honey, cumin, chili powder, and pepper.
Place the flank steak in a large, shallow dish or a resealable plastic bag. Pour the marinade over the steak, ensuring it's evenly coated. If using a bag, seal it, removing as much air as possible.
Refrigerate and let the steak marinate for 2-4 hours, turning occasionally if possible.
Remove the steak from the refrigerator 30 minutes before grilling to allow it to come to room temperature.
Preheat the grill to medium-high heat (about 400-450°F).
Remove the steak from the marinade, discarding any excess. Pat the steak dry with paper towels and season lightly with salt.
Grill the flank steak for 4-5 minutes per side for medium-rare, or adjust time for desired doneness. The internal temperature should reach 135°F for medium-rare.
Transfer the steak to a cutting board and let it rest for 5-10 minutes.
Slice the steak thinly against the grain.
While the steak is resting, warm the tortillas on the grill for about 30 seconds per side.
To assemble the tacos, place a few slices of steak on each tortilla. Top with pico de gallo or chopped tomatoes, avocado slices, cilantro, and crumbled cheese.
Serve immediately with lime wedges and hot sauce on the side if desired.