Meanwhile, combine dried chile and 1 ½ cups of water in a pot and boil the chile for 5-8 minutes until soft. Drain out the water and set it aside.
To make the tamarind juice, combine a ping pong ball size wet tamarind and water in a bowl. Using your fingers, squeeze and mash the tamarind until it dissolves. You'll get a dark brown liquid.
Place jalapeño, softened dried chile, shallots, tamarind juice, kombu, and its liquid in a high-speed blender. Blend the chile into a fine paste. This yields about 3-4 cups of mixture.
Heat a large wok or non-stick skillet, then add 1 ½ cups of oil.
Fry the peanuts for 1-2 minutes or until the skin turn slightly darker. Remove and transfer to a paper towel to absorb excess oil. The peanut will continue to cook and turn crispy once cooled.
Using the same wok, sauté onion until fragrant, about 2 minutes.
Then, slowly add the chile paste along with a knotted pandan leaves.
Cook for about 40-45 minutes, stirring frequently over medium heat. The sambal is ready when the chile turns darker red or oil starts to separate from the chile. It's best to cover the wok with a lid to prevent splatter and stir to avoid burning the chile.
Once the chile is ready, season with sugar, salt, and mushrooms seasoning. Turn off the heat and store it in a jar once cooled.