In a food processor, combine the mushrooms, oats, lentils, parsley and spices (oregano, red pepper flakes, thyme and tarragon). Pulse/blend until the mixture is pretty well pulverized but not mush (see photos).
Preheat oven to 400 degrees Fahrenheit and line a baking sheet with parchment paper. Combine lentils, bay leaf, and vegetable broth/water in a medium saucepan. Bring to a boil, then reduce heat to low and simmer for 10 minutes. (Don't worry, you want the lentils to be a little undercooked.) Remove from heat, drain and let cool for a few minutes. Discard the bay leaf.