Vegan or vegetarian bacon, which my wife calls Fakon, is a meat substitute for those who do not eat animal products. There are several brands, including Morningstar Farms®, Smart Bacon®, and Vacon.
Vegan bacon is normally made out of tofu slices or tempeh and flavored with spices, soy sauce, and Liquid Smoke®. It's easy to make your own by using the mentioned ingredients to marinade and then putting it in an oven set for 350 degrees Fahrenheit for 12 minutes per side. For spices I would recommend a bit of garlic, onion powder, and some cracked black pepper and salt to taste.
Other methods of making vegan bacon include using coconut meat or Seitan. I would recommend you try one of the commercial varieties first to see if you like it and then to see if you can replicate the flavor to your taste.
Iron Noder 2017