Need a suggestion for Tamarind paste substitute

Tamarind paste gives a sweet partly tart or sour note.
If it's a very small amount, you could leave it out.
If it's a larger amount and/or you want to replace it, try one or a combination of:
Lemon juice
(Regular) molasses
Pomegranate molasses (or syrup)
Sumac (for sour)
Mango chutney
A few blackberries, crushed