why bother? because it's sooooo delicious. Since there's so much acidity- tomatoes, vinegar - it will keep for around a month in your fridge. But trust me, you'll use it up long before then.
(As a side note - if you love homemade ketchup, with St. John's bread and Monteforte cheese in gooey grilled cheese sandwiches, along with many other delicious foods, you should come to Wychwood barns on Saturday mornings! There's a year-round farmer's market, and The Stop runs a Market Cafe, from 9AM to noon, where all sorts of brunch/lunch foods are served. I volunteer there, along with some other very talented cooks, so I can vouch for how tasty and mouthwatering the food is - and all the profits go back into The Stop's amazing food and gardening programs.)
1 tbsp olive oil
1 onion, diced
3 cloves of garlic, minced
2 cans of whole tomatoes, including juice
1/2 cup brown sugar
1/2 cup cider vinegar
salt and pepper
freshly grated nutmeg
2 tbsp dry mustard powder
pinch of cayenne
Saute onions and garlic in olive oil, until onion is translucent. Add all other ingredients, and simmer on medium-low heat for 45 minutes. Stir every once in a while, to make sure there's no sticking in the bottom of the pan. You might want to keep it partially covered, because there will be spattering. After 45 minutes, taste it! Add more sugar, vinegar or salt to you liking. Finally, puree with an immersion blender, or with a blender. If you like really thick, glossy ketchup, you can return it to low heat, and cook for another 10-20 minutes, but you have to watch it closely and stir often to keep it from burning. Really, this step is only if you want to go the extra mile.
Store in a container in the fridge for up to a month. Eat with grilled cheese, eggs, oven fries, where ever you'd eat that bland, sugary heinz ketchup (which will never look the same, after you taste this upgrade!).