Rehydrate mushrooms (if using dried): Cover with hot water 15–20 minutes. Squeeze dry, reserve soaking liquid (strain to remove grit), and slice caps.
Prep aromatics: Slice garlic and ginger; cube winter melon and tofu; thinly slice scallions (keep whites and greens separate).
Bloom aromatics: Warm oil in a 4–5 qt pot over medium heat. Add garlic, ginger, and scallion whites ; sauté 30–60 seconds until fragrant (do not brown).
Build broth: Pour in broth (and 1/2–1 cup/120–240 ml strained mushroom soaking liquid if using), soy sauce/tamari, salt, and white pepper. Bring to a gentle boil.
Simmer melon & mushrooms: Add winter melon and shiitake. Reduce to a lively simmer; cook 10–12 minutes until melon turns slightly translucent and tender.
Add tofu: Gently slide in tofu; simmer 3–5 minutes to warm through. Stir in sesame oil and rice vinegar (if using). Taste and adjust salt/soy.
Garnish & serve: Ladle into warm bowls. Top with scallion greens , cilantro, and optional chili crisp or fried shallots. Serve immediately.