If using Tamarind pulp, separate the 2 cups of water from the 1 litre. Boil this together with the tamarind pulp until pulp is loose and melted. Strain the liquid to extract the juice then set this aside. Continue to next step if not using Tamarind Pulp.
In a pot add onions, chillies, tomatoes and radish then pour water. Bring to a boil.
Once boiling add shrimps and tamarind mix (if using), simmer for 5 minutes.
Add spinach leaves then simmer for 2 more minutes.
Season with fish sauce and freshly ground black pepper.
NOTES
- Sinigang is usually sour but if you find it too sour add more water, or if find it not sour just add more Tamarind Mix or Tamarind Pulp