In a large saucepan, warm the olive oil over medium heat. Add the onion and garlic then stir to combine. Season with salt and pepper then sauté for 5 to 6 minutes, until the onion is translucent.
Stir in the mushrooms and turn heat to medium-high. Cook for an additional 5 to 10 minutes, until most of the liquid released from the mushrooms has cooked off.
Add the basil, canned tomatoes and their juices, tomato paste, salt, oregano and thyme then stir to combine. Next, add the red pepper flakes, chia seeds, and split peas or lentils, if desired, and stir to combine.
Reduce the heat to medium and simmer while stirring every so often. Cook for 15 to 20 minutes and serve over pasta.