Position a rack in the upper third of the oven and preheat to 475 degrees F. Separate 1 egg; set the yolk aside. Whisk the egg white, chili powder and 1/2 teaspoon salt in a large bowl until frothy. Add the potatoes, onion and poblano; toss. Coat a baking sheet with cooking spray; spread out the vegetables, then coat with more cooking spray. Bake, flipping once, until golden brown, 25 to 30 minutes.
Meanwhile, toss the tomatoes, 2 tablespoons cilantro and 1 tablespoon hot sauce in a bowl; season with salt and set aside.
Whisk the reserved egg yolk and 7 eggs with 1/4 cup cilantro and 1/2 teaspoon salt in a bowl until frothy. Melt the butter in a medium nonstick skillet over medium heat; swirl to coat. Add the egg mixture and cook, stirring, until just set, about 5 minutes.
Toast the tortillas in a dry skillet or wrap in a damp paper towel and warm in the microwave. Toss the remaining 2 tablespoons cilantro and 1 tablespoon hot sauce with the vegetable mixture. Divide the vegetables and scrambled eggs among the tortillas. Serve with the tomato salsa.