Heat skillet over medium high heat and add oil until shimmering.
Stir in the onions, garlic, mushrooms, anchovy paste, tomato paste, pepper flakes, and oregano to the pan.
Cook for 8 to 10 minutes, until the onion is beginning to brown. Stir in the wine and scrape up any browned bits.
Cook about 5 minutes, until thickened.
Pour the tomatoes and soy sauce into a slow cooker; add the onion mixture.
Cook on low for 9 to 11 hours.
Stir in the brown sugar and basil.
Serve immediately or store in airtight containers.
Notes
*Because I don't like a chunky sauce and find I can sneak more veggies in if I don't see them, I took my immersion blender to the sauce at the very end just to smooth things out. I froze my leftovers in ziplock bags