For the piri piri seasoning: Add the coriander and cumin seeds to a small cast-iron skillet over medium heat. Toast, stirring often, until fragrant and slightly smoky, 2 to 3 minutes. Place in a mortar and pestle and ground to a fine powder. Add the smoked paprika and mix to incorporate. Set aside.
For the chicken wings: Preheat the oven to 250 degrees F. Line a baking sheet with parchment paper.
Place the wings in a large bowl. Toss with the baking powder (this draws out the moisture), then with the salt, pepper and 1 tablespoon piri piri seasoning. Place the wings on the prepared baking sheet in an even layer (do not crowd the baking sheet; you may need to do this in batches or on 2 baking sheets). Bake 25 minutes. Turn the oven temperature to 475 degrees F and continue to bake until golden brown, 20 minutes more.
For the piri piri sauce: Combine the red peppers, chiles, garlic, oil, vinegar, sugar and remaining piri piri seasoning (about 3 tablespoons) in a blender, along with the cayenne if you like it spicy. Season with salt and pepper, then blend until smooth. Taste and adjusting the seasoning and heat to your palate.
Place the wings in a large bowl and toss with half of the sauce. Serve with the remaining sauce on the side for dipping. Garnish with the cilantro.