Preheat the oven to 375ºF. Line a large rimmed baking sheet with parchment paper.

Pour the olive oil into a large skillet over medium heat. When it shimmers, add the onion and garlic. Sauté until the vegetables are tender and lightly browned, 6 to 8 minutes. Stir in the chipotle, cumin, and salt and cook until fragrant, about 30 seconds. Add the cremini and shiitake mushrooms and cook, stirring occasionally, until the mushrooms exude their liquid and it evaporates and they start to brown, about 8 minutes. Transfer to a large bowl and let cool slightly.

Add the kidney beans, walnuts, aminos, chickpea flour, nutritional yeast, and lime juice and stir to thoroughly combine. Taste and add more salt if needed.

Lightly oil a ½-cup measure. Use it to scoop out six portions and use your wet hands to form them into large patties, about 5 inches across and ½ to ¾ inch thick. Place the patties on the lined baking sheet.

Bake the patties until firm and dry on the outside, about 30 minutes, flipping them over about halfway through. Transfer to a cooling rack to cool.

(At this point, you can wrap the patties in plastic wrap, seal them in zip-top bags, and refrigerate for up to 1 week or freeze for up to 6 months. Thaw them thoroughly before proceeding.)

Pour the vegetable oil into a large skillet over medium-high heat. When it shimmers, add as many patties as will fit without overcrowding. Fry until browned and crisp on the bottom, about 5 minutes, then carefully flip them over and fry until browned and crisp on the other side, about 4 minutes. Transfer to a platter.

Serve on buns with your preferred condiments and accompaniments.