If using wooden skewers, soak them in water for at least 30 minutes prior to grilling.
Preheat charcoal grill, or a gas grill or grill pan on medium heat. In a medium bowl toss together steak, mushrooms, broccoli, cumin, paprika, ½ tsp salt, ¼ tsp pepper and 2 tbsp extra virgin olive oil.
Thread beef, mushrooms, and broccoli onto skewers in an alternating pattern (if you have any additional pieces that don't fit on the skewers, they can be grilled unskewered). Grill for about 4-6 minutes per side to until meat is charred and vegetables are tender.
While skewers are on the grill, combine arugula, kale, carrots, and beets in a salad bowl. Zest lemon into a small bowl. Juice lemon and add 1 tbsp to the small bowl. Add 1 tbsp olive oil and whisk together. Add to salad bowl along with a heavy pinch of salt and pepper. Toss salad together.
Toast flatbreads if desired. Brush finished skewers with Japanese BBQ or teriyaki sauce. Serve skewers with salad and flatbread.