Whisk together the flour and nondairy milk in a small bowl, until smooth.
Combine the panko, nutritional yeast, onion powder and salt in a medium bowl.
Dip one piece of avocado into the milk mixture and submerge until coated. Allow excess liquid to drip off, then gently dip it in the panko mixture until coated. Place on the prepared baking sheet and repeat with the remaining avocado wedges, spacing them apart on the sheet.
Bake in the preheated oven for 25 minutes, flipping after 15 minutes, until golden brown.
Cashew Cream Sauce
Meanwhile, place the cashews, water, lemon juice, nutritional yeast, salt, garlic powder and Dijon mustard in the blender. Blend on high speed for 1 to 2 minutes, until smooth and creamy.
Divide the arugula between the English muffin halves, followed by the tomato and avocado fries. Evenly pour the sauce overtop; serve.