Preheat the oven to 400 degrees. Slice the corn tortillas into quarters and spread them on a parchment-lined baking tray. Sprinkle with salt, drizzle with olive oil, and toast them in the oven until crispy. Alternatively, use tortilla chips.
Make the cashew cheese: Soak the cashews in 1 cup water and set aside. Combine the agar and the remaining ¼ cup water in a saucepan and bring to a boil. Reduce the heat and simmer for 5 minutes, stirring continuously, until the mixture thickens. Put the cashews and soaking water, tahini, garlic powder, onion powder, and lemon juice in a blender and puree. Add the agar mixture and blend for 3-5 minutes until the mixture starts to thicken. Salt to taste, and refrigerate the “cheese” while you assemble the rest of the nachos, allowing it to thicken while it rests.
Make the taco "meat": Combine the TVP, ½ cup water, soy sauce, olive oil, cumin, coriander, garlic powder, and onion powder in a small saucepan and bring to a boil. Turn off the heat and let sit for 10 minutes.
Make a quick guacamole by mashing the avocado with a squeeze of lime juice and a pinch of salt.
In a small bowl, combine the chopped tomato, onion, cilantro, and jalapeño with a squeeze of lime to make a pico de gallo. Salt to taste. (Store-bought pico works here too.)
Assemble the nachos with the corn tortillas, cashew cheese, taco meat, quick guacamole, pico, scallions, and black beans.