1. Dry out tofu.
2. Trim 4 scallions and finely slice on a diagonal. Set 2 Tbsp. aside for serving.
3. Scrape skin from one 5" piece ginger (yes, it's a lot!) with a spoon. Slice off any exposed woody bits. Grate ginger and 4 garlic cloves on the small (shredding) holes of a box grater, then run your knife through them a couple of times to ensure no larger bits remain. (You can also use a Microplane, but a box grater is faster for this volume of aromatics.)
4. Mix 2 Tbsp. plus 1½ tsp. light soy sauce, 1 Tbsp. plus 1½ tsp. mirin, 1 Tbsp. plus 1½ tsp. toasted or untoasted sesame oil, 2 tsp. ground cumin, 1 tsp. ground turmeric, ¼ tsp. kosher salt, and ¼ tsp. coarsely ground black pepper in a small bowl.
5. Heat 4 Tbsp. unsalted butter in a wok or large skillet over high. As soon as butter is foaming, add scallions, ginger, and garlic and cook, stirring constantly to keep from sticking, until ginger and garlic begin to soften and scallions are wilted and slightly darkened in color, about 2 minutes.
6. Pour soy sauce mixture into pan and cook, stirring, until sauce is reduced by half, about 1 minute.
7. Add 7 oz. baby spinach (about 8 cups) a handful at a time, letting each batch wilt slightly before adding more if needed, then cook, stirring, until all of the greens have wilted a bit, about 2 minutes.
8. Place tofu in pan, gently breaking apart into 1" pieces, and cook, stirring gently with a wooden spoon or heatproof rubber spatula to incorporate, until warmed through and coated in sauce, about 3 minutes. Taste and season scramble with more salt and pepper if needed.
9. Divide scramble among plates. Top with fried shallots and reserved scallions, dividing evenly, and drizzle with chili oil to taste. Serve with toast alongside.