1 ½ cups water (adjust according to consistency preference)
1 medium-sized tomato, chopped
1 tbsp tamarind paste (or 1 small lemon-sized ball of tamarind soaked in warm water)
1 tsp turmeric powder
1 ½ tbsp jaggery (or sugar)
Salt, to taste
1 tbsp ghee (clarified butter) or oil
1-2 dried red chilies
1 sprig curry leaves
½ tsp mustard seeds
1 ½ tbsp chopped fresh coriander leaves
1 ½ tbsp chopped fresh cilantro (for garnish)
1 tbsp minced ginger (optional)
½ tsp hing (asafoetida) (optional)
Instructions:
Step 1: Preparing Rasam Powder
Roast the spices: Begin by dry roasting the coriander seeds, cumin seeds, black peppercorns, dried red chilies, toor dal, mustard seeds, and fenugreek seeds (if using) in a small pan over low heat. Keep stirring the spices to avoid burning. Roast them until they release a fragrant aroma, which should take about 2-3 minutes.
Grind the spices: Let the roasted spices cool down a bit, then transfer them to a spice grinder or a mortar and pestle. Grind the mixture into a coarse powder. You can grind it finer if you prefer, but traditionally, rasam powder has a slightly coarse texture.
Step 2: Preparing the Rasam Base
Tamarind extraction: If you are using tamarind paste, dissolve it in warm water and set aside. If you are using fresh tamarind, soak the tamarind in warm water for 15 minutes, and then extract the pulp by squeezing the tamarind in the water.
Cooking the tomato: In a saucepan or a deep vessel, add the chopped tomatoes and a pinch of turmeric powder. Cook the tomatoes over medium heat until they soften, which should take about 5 minutes. If you prefer a smoother rasam, you can mash the tomatoes after cooking.
Step 3: Cooking the Rasam
Adding the tamarind water: Once the tomatoes have softened, add the tamarind water to the pot. Add the jaggery or sugar at this stage for a touch of sweetness, balancing the tanginess of tamarind.
Adding water and rasam powder: Add 1 ½ cups of water to the pot and bring it to a boil. Once boiling, lower the heat and add 1-2 tablespoons of the freshly ground rasam powder. You can adjust the quantity depending on how flavorful you want the rasam.
Simmer: Allow the rasam to simmer on low heat for about 8-10 minutes. This will help all the flavors meld together. Taste it and adjust salt and sweetness if needed.
Step 4: Tempering the Rasam
Tempering (Tadka): In a separate small pan, heat ghee or oil over medium heat. Add mustard seeds to the hot oil. Once they start to splutter, add dried red chilies, curry leaves, and minced ginger (if using). You can also add a pinch of hing (asafoetida) at this stage for a more authentic flavor.
Combining the tempering with rasam: Pour the tempering over the simmering rasam. Stir gently to combine the flavors.
Final touches: Add freshly chopped coriander leaves (cilantro) to the rasam for added fragrance and color.
Step 5: Serve
Allow the rasam to simmer for another minute or two to infuse the tempering flavors.
Serve hot with a bowl of steamed rice. You can also enjoy it as a soup with a side of crispy papad (fried lentil crackers).