• Stir together 6 tbsp pesto, olive oil, cilantro, lime juice, garlic and cumin. Transfer steak and marinade to resealable plastic bag. Refrigerate for at least 4 hours or up to overnight.
• Preheat grill to medium-high heat; grease grate well. Pat steak dry with paper towels to remove excess moisture; season with salt and pepper. Grill for 4 to 5 minutes per side for medium-rare or until cooked as desired. Let stand for 5 minutes; slice thinly.
• Assemble steak, tomatoes, Cheddar and green onions in warm tortillas. Drizzle with remaining pesto. Serve with lime wedges.

Tips:

• Substitute crumbled queso fresco or feta for Cheddar cheese if desired.
• Spice up the tacos with pickled or fresh jalapeño slices.
• To make this dish gluten-free, substitute flour tortillas for corn tortillas.