Heat your grill to medium-high for at least 15 minutes.
In a large bowl, mix together the spices and ¾ teaspoon salt. Sprinkle evenly over the salmon flesh. Drizzle olive oil over top and rub it all around to coat the flesh. Brush the tomatoes with some olive oil (if using).
Add the salmon, tomatoes, and jalapeno (if using) to the grill. Grill for 6-8 minutes, covered, or until the tomato and jalapenos are charred/ softened and salmon is mostly cooked through. Flip the salmon and cook for about 2 more minutes, or until salmon is cooked though (easily flakes with a fork).
Transfer tomatoes and jalapeno to a cutting board, chop them up, and transfer to a small bowl along with remaining ¼ teaspoon salt and juice from ½ of a lime. Transfer salmon to a plate or cutting board and use two forks to flake into bite-sized chunks.
In a medium bowl, add the cabbage, cilantro, lime juice, and salt and toss to combine.
In a small bowl, mash up the avocado as best you can. Mix in the yogurt, lime juice, and salt until thoroughly mixed. Taste and add more salt or lime, if needed (you may need more salt depending on the size of your avocado).
Warm up your tortillas and top with flaked salmon, cabbage, grilled tomatoes, and avocado crema.