In a skillet, heat olive oil over medium heat. Add diced pumpkin and sauté for about 5 minutes, until slightly tender.
Add the cod fillets to the skillet, seasoning with salt, pepper, garlic powder, and dried basil. Cook for 8–10 minutes, flipping once, until the cod is cooked through and flakes easily. Remove from skillet and set aside.
In the same skillet, add chopped kale and cook until wilted, approximately 3 minutes. Stir in the crushed tomatoes and tomato paste, cooking for another 2-3 minutes until well combined.
Return the cod to the skillet, gently mixing to coat in the tomato basil sauce. Heat through for an additional minute.
Warm the corn tortillas either in a skillet or microwave for a few seconds until pliable.
To assemble, place a generous portion of the cod and kale filling onto each tortilla. Fold in half or leave open-faced, as preferred. Drizzle with tahini, top with avocado slices and cilantro, if using. Serve with lime wedges and a side salad.
