Heat the olive oil over low heat. Add the onions and 1/2 teaspoon salt, and sauté the onions until caramelized (mine took 35 minutes).
While the onions are cooking, remove the tofu from the package and drain off any liquid. You won't be able to remove all of the moisture, and that's totally OK. Just do your best to blot out some of the water.
With a blender or food processor (a stick blender is ideal), puree the tofu, cashews, lemon juice, onion powder, and the other 1/2 teaspoon of salt until creamy and smooth.
Stir in the caramelized onions and 1 tablespoon of chives. Give a taste and add more salt, if desired.
Transfer the dip to a serving bowl and refrigerate for 1 hour, or up to 48 hours (I haven't tried anything longer). When ready to serve, top with the remaining 1 tablespoon of chives.