Put the shrimp in a medium bowl and sprinkle with salt and pepper. Crack the coriander seeds on a cutting board with the flat side of a chef’s knife; add to the shrimp along with the olive oil, chili powder, cumin and oregano and mix until evenly coated. Refrigerate the shrimp while you make the sauce.
Pulse the basil, cilantro, scallions, anchovy and garlic in a food processor until finely chopped. Add the sour cream, mayonnaise, lime juice, avocado flesh, 1 teaspoon salt and a few grinds of pepper. Process until very smooth, scraping down the sides as needed. Season with more salt and pepper if desired. Transfer to a serving bowl.
Prepare a grill for medium-high heat.
Thread the shrimp onto 5 to 6 metal skewers and drizzle with olive oil. Drizzle the corn with olive oil and season with salt and pepper. Place the corn on the grill and cook, rotating periodically, until lightly charred all over, about 8 minutes. Grill the shrimp skewers, turning halfway through, until lightly charred and cooked through, 2 to 3 minutes total. Grill the tortillas until lightly charred and pliable, 30 to 60 seconds per side; wrap in foil to keep warm.
Serve the grilled shrimp with the warm tortillas, green goddess sauce, lettuce, tomatoes, cilantro, basil, jalapeños, Cotija and lime wedges. Cut off the corn kernels and serve with the other toppings.