Place the chopped potatoes in a pan. Pour in the water and bring to a boil. Cook until the potatoes are fork tender.
While you're waiting for the potatoes to cook, place the chopped onion in a lidded container, large enough to hold the finished potato salad. I used a large, round pyrex dish.
When the potatoes are done, carefully pour them into a strainer to remove excess liquid. The water will be hot so be careful. When the potatoes are drained, pour them over the onions, and place the lid on the container to seal it. That will allow the onions to soften with the hot potatoes.
Hopefully by now you've already prepared your Tofu Scramble, but if you haven't, now's a good time to do that.
In a small bowl, combine the mayo, mustard, vinegar, and sweet pickles. Stir to combine. Add one tablespoon of sugar, stir, and then take a little taste to see if it meets your expectations of sweetness. Some people, like my mom, like their potato salad a little more on the sweet side. Continue adding sugar, one tablespoon at a time (or leave it as is until you get it just right).
If you'd like, go ahead and add some finely chopped celery to the mix. It can make for a crunchier potato salad, but I'm not so certain I prefer the distraction from the potatoes. What I really like is adding a teaspoon or os of celery seed so I can have a little of the flavor of celery without all that annoying crunching. If you'd like to give that a try, add 1 teaspoon of celery seed to the mayo mixture.
Pour the mayo mixture over the potato salad and give it a good, gentle stir, being careful not to mash the tender potatoes. (They can be so sensitive!) Add the scrambled tofu and stir some more, until everything is well-combined.
Refrigerate, preferrably an hour or two before serving.