heat the oil in a medium pot over medium-high heat, add the onion, and cook until softened and starting to color. Add the turmeric and cardamom and stir to coat the onions. Add the carrots, the water, and the tamarind, and simmer for 20 minutes or until the carrots are soft.
add the tahini and 1 teaspoon of salt, and blend with an immersion blender until completely smooth.
add the lime juice and a good grind of salt and pepper. taste, and adjust seasoning. i needed another good pinch of salt at this stage.
Recipe by The Bright Kitchen at https://www.thebrightkitchen.com/carrot-tahini-soup/