- Thoroughly rinse fresh produce under warm running water for 20 seconds. Scrub to remove excess dirt.
- Preheat oven to 350 degrees. Coat a baking sheet with cooking spray.
- Heat a large skillet over medium-low heat. Add 1 tablespoon olive oil and onion. Sauté onion until soft. Add garlic, mushrooms, and red pepper flakes. Season with salt and pepper to taste. Cook until mushrooms are brown, 5 to 8 minutes. Remove skillet from heat and transfer mushroom mixture to a large bowl to cool, at least 10 minutes.
- Add panko, breadcrumbs, carrots, lentils, and herbs to mushroom mixture. Season to taste with salt and pepper. Add eggs and stir to combine. Divide mixture into 8 patties.
- Reheat skillet over medium-low heat. Add the remaining 2 tablespoons olive oil. Cook each patty until golden brown, 3 to 4 minutes per side.
- Transfer patties to prepared baking sheet. Bake until cooked through, about 10 minutes. Internal temperature of patties should be 145 degrees using an instant-read thermometer. Serve warm.