Heat the olive oil in a large skillet or Dutch oven over medium heat. Add the onion, carrots, and celery, and cook for 5–7 minutes until softened. Stir in the garlic and cook for another minute until fragrant.

Stir in the chopped mushrooms and cook for 5–7 minutes, allowing them to release their moisture and brown slightly. This step builds a deep, umami flavor.

Add the lentils, dried oregano, dried basil, and red pepper flakes (if using). Stir to coat the lentils in the vegetable mixture. Add the tomato paste and cook for 2–3 minutes to caramelize slightly.

Pour in the crushed tomatoes and vegetable broth, stirring to combine. Bring the mixture to a boil, then reduce the heat to low.

Cover and simmer for 30–35 minutes, stirring occasionally, until the lentils are tender and the sauce has thickened.

Stir in the plant-based milk and season the sauce with salt and black pepper to taste. Let it cook for another 5 minutes to bring everything together.

Serve the lentil Bolognese over your favorite pasta, zoodles, or polenta. Garnish with fresh parsley or basil if desired.