Dice tomatoes and move to a parchment-lined sheet pan.
Freeze overnight.
Add the frozen tomatoes to a large mesh sieve or a cheese cloth-lined colander set atop a large bowl.
Let the tomatoes thaw out for 8-12 hours in the refrigerator, or until completely defrosted.
Strain the tomato water by passing it through a cheese cloth or a paper towel.
Store in the fridge for a few days (~3 days).
For long term storage, freeze it in ice cube trays.
