Mix all ingredients in a food processor. It should be the consistency of play dough. Oil a 9" pan with olive oil, including the sides of the pan. Oil your hands as well.
Spread the dough out in the pan, including the sides, pressing down to get it even. Bake at 350°F for 20-25 minutes, or until the edges are starting to turn golden.
Filling
Heat the olive oil in a pan on medium-low heat. Add sliced onions. Sprinkle salt on onions.
Stir the onions every few minutes or so. Cook about 35-40 minutes until they are well-browned. Add a small amount of water if they start to stick. Add balsamic vinegar and cook until it's evaporated.
In a food processor, mix caramelized onions* - reserving ¼ cup to place on top, tofu, tamari, miso paste, nutritional yeast, and salt and pepper to taste.
Spread filling on chickpea flour crust. Sprinkle reserved onions on top. Bake at 400°F for 20-25 minutes, or until browned.
Notes
If you prefer chunky caramelized onions in the quiche, add them last and pulse until you get the desired consistency.This recipe will last about 5 days in an airtight container in the fridge.