Preheat a 3 1/2 quart sauce pot over medium heat. Add olive oil.
Next add onions and sautee for 5 - 6 minutes, stirring often, or until translucent and soft, but not caramelized. Add garlic and stir for another minute.
Add ketchup, tomato puree, molasses, and apple cider vinegar and bring to a simmer. Should take about 5 minutes to come to a simmer.
Finally add sugar, salt, cayenne, and black pepper and stir. Using a hand immersion blender, blend the ingredients to grind up the onion and garlic.
Bring back to a simmer and cover for another 20 minutes. Remove from heat, and then using a funnel, pour the sauce into a mason jar.