Tamarind is actually a fruit. It's the main ingredient in authentic Pad Thai sauce. It's quite tart, but is perfect for Thai dishes, which balance tart, sweet, salty and spicy flavours. You can usually find it in ethnic food shops and health food stores.
You can adjust the flavour to taste, by adding more sugar or heat, depending on your preference.
1 tsp peanut or canola oil
1 lb boneless, skinless chicken, cut into bite sized pieces
1 tbls corn starch
1 onion, thinly sliced
3-4 cloves garlic
large knob of fresh ginger, cut into 3-4 pieces
1/2 cup tamarind concentrate (puree)
1/4 cup ketchup or 2 tbls tomato paste + 1 tbls brown sugar
4 tbls rice vinegar
2 tbls fish sauce
Juice of 1 lime
1 bunch green onions, thinly sliced
A few handfuls fresh coriander (cilantro), roughly chopped
Combine all ingredients for sauce in food processor or blender and Toss chicken with corn starch. Heat wok or skillet and stir fry chicken and onion in oil. When chicken is no longer pink, add sauce and cook a few more minutes. Add green onions and coriander just before serving. Serve over brown jasmine rice.
Crushed hot chili flakes, to taste