Step 1

Add the vegetable broth, 1 cup water, shiitakes, ginger, garlic, and instant dashi to a 6- or 8-quart Instant Pot® multi-cooker. Follow the manufacturer's guide for locking the lid and preparing to cook. Set to pressure cook on high for 5 minutes (see Cook's Note).

Step 2

After the pressure-cook cycle is complete, follow the manufacturer's guide for quick release and wait until the quick-release cycle is complete (this should take about 1 minute). Being careful of any remaining steam, unlock and remove the lid. Use a slotted spoon to remove the coins of ginger and discard.

Step 3

Turn the pot to the high saute setting (this will keep the soup warm). Whisk in the white miso paste until dissolved, then gently stir in the tofu, scallions and mirin if using. Ladle into bowls and serve immediately.