Ground the onions, fresh chilies, dried chilies, garlic and lemongrass together to make a paste. If you find it difficult to ground these ingredients together you may use a few teaspoons of sunflower oil to this mixture.
Take a wok or frying pan and heat five table spoon of oil. Once the oil is moderately hot you can add the mixture and sauté.
Add the turmeric powder to the mixture.
Cook the mixture in low heat and constantly stir it to ensure that the mixture does not stick to the pan. (After some time the paste will leave a pleasant aroma.)
Fifteen minutes after constantly stirring the mixture, add the sugar, salt and tamarind juice.
Allow the paste to cook and remember to stir occasionally. When you see the oil from the paste floating on the top, you will know that the sauce is ready.
After this you can can let the sambal cool down and taste it!
You can also store the extra sauce after cooling it down. Put the sauce in a container and store it in a freezer to use for a few more days.