A question about a recipe: Shrimp Pad Thai

Tamarind concentrate is a reduced paste made from tamarind fruit. It is sweet, dark and very sticky; I think of it as somewhat raisin- or dried fig- like in flavor. Fish sauce is made from fermented small fish with lots of added salt. It is very thin in consistency and used in small quantities for flavor. It smells weird fright rom the bottle but it really adds great flavor to dishes. I see fish sauce in the Asian food section of my local grocery stores, but I think tamarind concentrate is a little harder to find. You can get it at Whole Foods and Indian grocery stores. Both are worth seeking out if you are making Pad Thai.