In a food processor, fitted with an S-blade, pulse cauliflower florets into rice. This usually needs to be done in batches, depending on container size. Alternatively, you can use one 16-oz package of pre-riced cauliflower and skip this step.
In a blender, combine cashews, nutritional yeast, lemon juice, apple cider vinegar, Worcestershire sauce, tamari, poultry seasoning, red chili flakes, black pepper, arrowroot, and almond milk. Purée until smooth and well-combined, about 60-90 seconds.
Heat a large saucepan or Dutch oven over medium-high heat. Once hot, sauté onions with as little water as possible, just enough to avoid burning, until they begin to brown, approximately 3-4 minutes. Add celery and jalapeño and continue sautéing, adding water as necessary, until soft, approximately 2 minutes. Add garlic and sauté for another 30-60 seconds, or until garlic is lightly browned, being careful not to scorch.
Add mushrooms and fresh herbs, if using, and cover. Allow mushrooms to sweat until the pan is filled with liquid. They will reduce significantly. Uncover and allow some liquid to evaporate, about 3-5 minutes. Combine cauliflower rice and blended sauce and stir to combine. Lower the heat and cook for 20 minutes, until thickened, stirring frequently. Add kale, if using, and stir until wilted.
Remove from heat and enjoy immediately or cool to room temperature and store in an airtight container in the refrigerator for up to 4-5 days.