In a medium-size bowl, combine the onion, carrot, cucumber, lime juice and tamari. Allow to sit for at least 15 minutes. In a separate small bowl, whisk together the mayonnaise, sriracha and lime zest.Slice the tofu crosswise into 1/2-inch-thick slabs. Add the cornstarch to a large shallow bowl with the garlic powder and a large pinch of salt & pepper, and whisk together. Dredge each piece tofu in the cornstarch mixture until evenly coated. Warm the oil in a large skillet over medium-high heat. Add the tofu and cook until crispy and light golden brown, about 4 minutes on each side. Transfer to a paper towel-lined plate.Serve tofu warm in corn tortillas, top with pickled vegetables, sriracha mayo, and fresh cilantro, then enjoy!