Preheat oven to 450°F. Line a small rimmed baking sheet with foil, and coat with nonstick cooking spray. Place salmon fillets on the prepared baking sheet. Pat dry. Season with salt and pepper to taste. Bake 8 to 10 minutes, or until salmon flakes easily with a fork. Meanwhile, in a small bowl, combine water, tahini, lemon juice, 1 tsp oil, garlic powder, 1/4 tsp salt, and 1/8 tsp pepper. In a large bowl, rub kale with the remaining 3 tsp oil and kosher salt. Divide prepared kale among four pint jars. Cut off a slice from both ends of the grapefruit. Cut away the peel and the white part of the rind (the pith), working from top to bottom. Working over a bowl to collect the juice, hold the grapefruit in one hand; tip the grapefruit to its side and cut into the center between one section and the membrane. Cut along the other side of the section next to the membrane to free the section. Set sections and juice aside. Top kale with salmon and garbanzo beans. Top with grapefruit sections. Peel, seed, and chop avocado. Place pieces in a bowl with grapefruit juice. Toss to coat. Divide avocado among pint jars. Drizzle with dressing. Cover and chill up to 3 days. Garnish with sesame seeds, if desired.