These tiny black teardrop shaped seeds are from the sacred basil plant. They are known by various names"sbza, subza, takmaria, tukhamaria, falooda, seilash (Malay/Indonesian) or hột é (Vietnamese.) In India they used in Muslim and Buddhist cuisine and as a medicinal herb. The use of ocimum sanctum is restricted by Hindus as it has a sacred association to the god Vishnu. Basil seed also appears in the cuisine of Indonesia, Thailand, Iran and Afghanistan. The two varieties I have found from which the seeds are harvested for culinary use are Sacred Basil, ocimum sanctum and Hairy Basil, ocimum canum. I don’t know if common Sweet Basil seed works in the same way.
The seeds themselves have little or no flavour. What they do have is the ability to soak up water to create a jelly rather like tapioca. As the little black seeds look like tadpoles hatching, there is also a textural similarity to caviar with a crunchy centre. Reputed to have cooling properties, they are mainly used to thicken drinks and desserts. In Iran they are teamed with lemon juice, in Vietnam with either young coconut milk or water flavoured with palm sugar. The most common use is in the Indian recipe for Falooda.
New research seems to indicate that the soaked,swollen seeds can act as an appetite supressant during weight losswhen eaten (or drunk) before meals.
For more on tukmaria see http://frompotionstopesto.blogspot.com/2010/06/tukmaria-diet-seed.html and