Rinse 2 cups of green or brown lentils under cold water. Place them in a pot and cover with water by 2 inches. Bring to a boil, then reduce to a simmer and cook for about 20-25 minutes until tender but not mushy. Drain and set aside.
Heat 2 tablespoons of olive oil in a large skillet over medium heat. Add the diced onion, carrot, and celery. Cook for 5-7 minutes until the vegetables soften and the onion becomes translucent. Add 2 cloves of minced garlic and sauté for another minute until fragrant.
Add the cooked lentils to the skillet with the vegetables. Stir in 1 can (28 oz) of crushed tomatoes, 1 teaspoon dried oregano, 1 teaspoon dried basil, salt, and pepper to taste. Mix everything well and bring to a gentle simmer.
Reduce the heat to low and let the sauce simmer uncovered for 15-20 minutes, stirring occasionally. This allows the flavors to meld and the sauce to thicken slightly.
While the sauce simmers, bring a large pot of salted water to a boil. Add 12 ounces of fusilli pasta and cook according to package instructions until al dente. Drain the pasta, reserving a splash of pasta water.
If the sauce is too thick, stir in a bit of the reserved pasta water until you reach your desired consistency. Toss the cooked fusilli into the skillet with the lentil bolognese or serve the sauce spooned generously over the pasta. Garnish with freshly chopped parsley.