Preheat the oven to 420°F (215°C). Line a baking sheet with a silicone mat or parchment paper.
In a medium mixing bowl whisk together the avocado oil, garlic powder, onion powder, paprika, and kosher salt until combined.
Tear the pressed tofu into bite-sized pieces for a meat-like texture, or cut into small cubes. Add the tofu to the bowl and gently toss with a spatula until evenly coated in the seasoned oil.
Sprinkle the cornstarch evenly over the coated tofu and toss again so each piece is lightly dusted.
Arrange the tofu pieces on the prepared baking sheet in a single layer, not touching. Bake on the top oven rack for 30–35 minutes, flipping once halfway through, until golden and crisp.
While the tofu bakes, combine the Frank's RedHot and agave in a small saucepan. Warm over medium heat until it begins to gently steam, then remove from heat and stir in the dairy-free butter until melted and combined. Set aside.
When the tofu is crisp, transfer it to a large bowl. Pour in 1/2 cup (120 ml) of the prepared buffalo sauce and toss with a spatula to coat evenly. Add more sauce to taste or serve extra on the side.
Serve the buffalo tofu warm with celery sticks and vegan ranch if using.