Preheat the grill to medium-high heat - around 400° F. If using wooden skewers, soak the skewers for 10 minutes to prevent burning. Season shrimp with salt and pepper, place on the skewers and brush with canola oil.
Grill for 2-3 minutes per side or until fully cooked. Reserve for tacos.
Combine the shredded cabbage, green onion, cilantro, and poblano pepper in a medium bowl. Stir to combine.
For Creamy Avocado Tomatillo Salsa, combine avocados and salsa in a blender. Pulse-blend a couple of times, then add lime juice, cilantro, garlic, and sour cream. Process until smooth, scrape into a bowl, and add salt to taste.
Warm tortillas. Distribute ingredients evenly across 4 tacos in the following order: Shredded Cabbage Salad, grilled shrimp, and Creamy Avocado Tomatillo Salsa.