
This tomato hot pot soup base is light, savory, and full of deep umami from shiitake mushrooms, ginger, garlic, and tomato paste. It comes together with simple pantry ingredients and creates a bright, well-balanced broth that pairs beautifully with vegetables, tofu, noodles, and thinly sliced meats.
Place the dried shiitake mushrooms in a bowl and cover with hot water. Soak for about 2 hours, or until softened. Rinse the mushrooms well, then strain and reserve the soaking liquid, leaving any grit behind.
Heat a wok or large pot over medium heat. Add the oil, bay leaf, ginger, and the white parts of the scallions. Cook for about 1 minute, stirring often, until fragrant.
Add the garlic and stir for 30 seconds. Mix in the tomato paste, sugar, and salt, then cook for 4 to 5 minutes, stirring frequently, until the paste darkens slightly and the oil takes on a rich red color.
Pour in the water along with the reserved mushroom soaking liquid, taking care not to add any sediment from the bottom of the bowl. Add the soaked shiitake mushrooms and stir well.
Bring the broth to a gentle simmer. Cover and cook for 10 minutes to let the flavors blend. Stir in the green parts of the scallions, then serve as a hot pot base with your favorite vegetables, tofu, noodles, or proteins.
If you want a richer broth, replace part or all of the water with vegetable or chicken stock. Taste the soup before serving and adjust with a little more salt or sugar if needed, since hot pot add-ins can dilute the broth. The soup base can be made up to 3 days ahead and refrigerated in an airtight container.