Dice up your onion
Heat a large saucepan and then add the oil
Add onion and let them brown a bit at medium to high heat
Take pan off heat
Add the salt, pepper, and oregano
Pour sauce into pan and mix everything together
Put back on medium heat
Cook down sauce for about 10 minutes
Add water and cook for another 5 minutes
Remove from heat and let sit for 10 minutes
Add the contents to a food processor
Add basil and pulse 15-20 times