1. Dip the tomatoes in boiling water for a minute.
2. Dip in 500 ppm solution of sodium metabisulfite for 2 minutes.
3. Dry in the oven at 54°C for 9 hours or until its moisture goes down to 7.5%.
4. Pulverize the dried tomatoes in a pestle.
The resulting product is red in color and smells and tastes like fresh tomatoes. To cook, mix with water as needed.