Core the tomatoes using a small paring knife. If you cut them as shown in the photo accompanying Step 2, it'll cause lumps. The tomatoes should be whole when you place them in your pot.
Fill up about 2/3 of the pressure cooker with tomatoes, and set to medium heat. Once the indicator pin pops up, heat for another 2 minutes then let cool.
During this time, grate the onion, garlic, and ginger (Put them into the food processor together).
Place a coarse mesh sieve over a pot and strain the contents from Step 2. Remove the skin with chopsticks, and press the rest through.
This is what it looks like after straining.
Add the bay leaves, set the heat to high, and cook while skimming off any scum.
After simmering, it will become a purée.
Add the remaining * ingredients and continue cooking (it burns easily after adding the onions so keep stirring constantly).
Pour into a storage container and it's done.
Story Behind this Recipe
I love making ketchup with a bunch of ripe tomatoes. This flavor is unforgettable.
Step 6 is cooked over high heat. Please remove the scum carefully (There's no need to worry about burning at this stage.) It burns easily once you add the onions, so be careful then. The most important point is the amount of salt. Feel free to taste test after adding a teaspoon. Even if there's not enough salt, it won't really taste like anything.