I love making homemade ketchup because I can season it to taste and this way it doesn't contain any high-fructose corn syrup.
This is an updated version of my ketchup recipe found here.
2 tablespoons tomato paste
1 teaspoon vinegar
1 teaspoon honey
1/4 teaspoon salt
Stir all ingredients together and taste-test. Add a bit more tomato, sweet (honey), sour (vinegar), or salt to taste.
For more flavor and dimension, add-in the optional ingredients. Makes enough for two people.
1/2 teaspoon Worchester sauce, 1/2 teaspoon molasses, and/or 1/4 teaspoon each onion and garlic powder