Make sure shrimp are completely thawed and patted dry with paper towels. In a large bowl, toss the shrimp with olive oil, chili powder, cumin, garlic powder, paprika, salt, and pepper until evenly coated. Do not add lime juice yet.
Mix the sour cream, mayo, lime juice, and hot sauce in a bowl. Cover and refrigerate until ready to use.
Turn all Blackstone burners to high and preheat the griddle for about 10 minutes until it reaches 400-425 degrees. Test by flicking water droplets on the surface - they should dance and evaporate immediately.
Oil the griddle surface with a squirt bottle and let heat for 30 seconds until shimmering.
Spread shrimp across the griddle in a single layer, making sure each shrimp has direct contact with the surface. Do not touch them for 90 seconds to develop char.
Flip each shrimp and cook for another 90 seconds on the other side until pink, opaque, and curled into a C shape. Total cook time should be about 3-4 minutes.
Remove shrimp from griddle and immediately squeeze lime juice over them and toss.
Turn one burner down to medium (300-325 degrees) and place tortillas directly on the griddle. Cook for about 30 seconds per side until lightly charred with brown spots and slight puffing. Stack on a plate and cover with a kitchen towel.
Build tacos by layering: tortilla, crema sauce, shredded cabbage, 4-5 shrimp, more sauce, cilantro, avocado slices, and a squeeze of fresh lime. Add optional toppings if desired.