I used a food processor, so that's the method I've described here. There's no reason you couldn't do this recipe by hand or even using a mixer or a blender. Be sure to finely mince the onion because you probably won't want chunks of onion in your dressing.
Purée onion in food processor. Add tomato paste, honey, vinegar and seasonings and pulse until blended. Add oil and pulse until mixed. Refrigerate.
This is a very basic recipe. Feel free to taste and add more of anything you feel it needs. I used expeller pressed coconut oil because it has no coconut flavor, but I think any neutral oil would work. I used a very light-flavored honey but a 2:1 simple syrup (2 parts white sugar to 1 part water, heated until the sugar dissolves) would work if you don't like honey, or even light corn syrup.