Start by making the avocado cream. Blend avocados, sour cream, lime juice, garlic, and cilantro in a food processor until smooth. Season with salt and refrigerate until ready to use.
Pat the shrimp dry with paper towels. In a bowl, combine chili powder, cumin, garlic powder, and smoked paprika. Toss the shrimp with olive oil and the spice mixture.
Heat a large skillet over medium-high heat. Cook the shrimp for 2-3 minutes per side until pink and slightly charred.
Warm the tortillas either in a dry skillet or wrapped in damp paper towels in the microwave for 30 seconds.
Assemble the tacos by spreading avocado cream on each tortilla, then top with shredded cabbage, seasoned shrimp, diced tomatoes, and fresh cilantro.