Soaking dried dates in boiling water softens them so they blend easily, lending their signature caramel-like sweetness to this tart chutney.
Place dates in a small heatproof bowl; cover with 1 1/2 cups boiling water. Let stand at room temperature until dates are softened, about 1 hour. Transfer softened dates and soaking water to a blender; add tamarind paste, lemon juice, salt, chile powder, and cumin. Process until smooth, about 35 seconds.
Store chutney in an airtight container in the refrigerator up to 5 days.