In small saucepan over high heat, bring water to a rolling boil. Break tamarind into small pieces and drop into boiling water. Boil for 3 to 4 minutes. Over large bowl, strain through fine-mesh sieve, pressing out every bit of liquid and paste. Discard pulp in sieve. Allow to cool before using.

In small food processor, pulse dried shrimp until they look stringy, almost like floss. Set aside. In small saucepan over medium heat, heat 1 tbsp of sunflower oil. Add chilis and cook until chilis turn dark red, 1 to 2 minutes. Transfer chilis to stone mortar and pestle. Return pan to medium heat. Add remaining ¼ cup of sunflower oil and heat for 1 minute. Add garlic and shallots and cook, stirring frequently, for 2 to 3 minutes. Remove from heat. Using slotted spoon, transfer garlic and shallots to mortar with chilis. Pound garlic and shallots to fine paste. Add paprika and pound to mix. Return pan to medium heat and allow sunflower oil to heat for 1 minute. Scoop paste out of mortar, add to oil and cook, stirring frequently, for about 2 minutes. Add shrimp floss, Tamarind Paste and coconut sugar. Reduce heat to medium-low and cook until sugar is fully dissolved, 1 to 2 minutes.

In medium pot over high heat, bring water to a rolling boil. When water is boiling, reduce heat to medium and add lemongrass, galangal, garlic, shallots and lime leaves. Boil for 5 minutes. Stir in Tom Yum Paste and boil for another 5 minutes. Without stirring, add shrimp, oyster mushrooms and tomatoes. Increase heat to high and cook, without stirring, for 2 to 3 minutes, or until shrimp are pink and opaque. Stir in Tamarind Paste and cane sugar, and cook for another minute. Stir in fish sauce and lime juice. Remove from heat. Stir in cilantro, green onions, sawtooth coriander and chilis. Ladle into bowls and serve.