Combine olive oil, lime juice, garlic, chili powder, cumin, salt, and pepper in a bowl; divide marinade between steak and shrimp, coating well.
Let steak and shrimp marinate separately for 15 to 20 minutes.
Heat a grill or skillet over medium-high heat.
Cook steak slices for 2 to 3 minutes per side until desired doneness, then remove and let rest.
Cook shrimp in the same pan for 2 to 3 minutes per side until pink and opaque, then remove from heat.
In a small bowl, mix sour cream, mayonnaise, and hot sauce to create the creamy sauce.
Warm tortillas in a dry skillet or microwave.
Assemble tacos by layering steak, shrimp, shredded cabbage, cilantro, and drizzle with creamy sauce.
Serve tacos with lime wedges on the side.