Seedless cucumber does a great job adding cooling crunch to avocado toast, but it doesn't impart much in the way of flavor. Here, soy sauce adds a savory note, amped up by a sprinkle of peppery scallions. But the real kicker is a pinch of shichimi togarashi, a Japanese seven-spice blend of chili peppers, sesame seeds, and other ingredients like nori, ginger, and orange peel, which adds nuanced heat to each bite.