Crumble the pressed tofu into the food processor, then add the smaller amounts* of the remaining ingredients. Process for several minutes until perfectly smooth, stopping and scraping down the sides as needed.
Taste and add more umeboshi (for saltiness and tang) and/or lemon (for sourness).
You should end up with a thick, rich cream.
*Because the flavor of different brands of tofu can vary, it’s best to start with the smaller amounts of each ingredient, then add more as needed.