Thai Tamarind Chicken Stir Fry

4 chicken thighs
1 cup Mushrooms sliced
2 thumb-size pieces ginger, sliced into matchstick-like pieces
3 cloves garlic
handful fresh corriander
2 tsp. cornstarch powder dissolved in 3 Tbsp. regular soy sauce
2-3 Tbsp. Oil
TAMARIND SAUCE:
2 tsp. tamarind paste
1/3 cup water
2 Tbsp. fish sauce
2 Tbsp. sugar
1-3 fresh chillies, or to taste

Place chicken pieces in a bowl and pour over the cornstarch and soy sauce mixture. Stir well to cover chicken with the sauce. Set near the stove to marinate while you make the tamarind sauce.

Make the tamarind sauce by mixing all sauce ingredients together in a cup (the tamarind paste and sugar should more or less dissolve in the water and fish sauce). Also set near the stove.

Pour 2-3 Tbsp. oil into a wok or large frying pan. When hot, add the garlic, ginger, mushrooms, and chicken (together with the cornstarch/soy sauce marinade).

Stir-fry 1-2 minutes, or until the wok or pan becomes dry. At this point, and continue stir-frying another 1-2 minutes.

When wok or pan becomes dry again, start adding the tamarind sauce 2-3 Tbsp. at a time, always when wok or pan becomes dry. Continue stir-frying in this way until all the sauce has been added and the chicken is cooked (8-10 minutes in total).
Remove from heat and adjust seasonings to taste.