Pad Thai cooks up very fast one you get the heat going. Be sure to have all your ingredients cut and measured out and your sauce mixed before you start cooking. Tamarind paste is a puree of the fruit without the seeds and fibers. You may also find tamarind concentrate, in which case you'll want to dissolve it in 1 tablespoon of hot water first. If you have thicker, large scallions, slice them in half lengthwise before cutting into pieces.