Preheat the oven to 350°F and line a baking sheet with parchment paper.
Place the pepitas, sunflower seeds and sesame seeds on the baking sheet, toss with the tamari, and spread evenly on the baking sheet.
Bake for 7 to 10 minutes, or until golden brown and toasty.
Remove from the oven and let cool for 5 minutes to allow the seeds to crisp up.
Arrange the tomatoes on a large platter in a single layer, overlapping only slightly.
Top with the avocado slices and scallions and drizzle with the lime juice and sesame oil. Sprinkle with flaky sea salt, the seed topping and microgreens.