Simmered Okinawan Purple Sweet Potato and Miso Soup

By AislePrompt Editorial · Published 2026-05-21 · Updated 2026-05-21

A nourishing soup featuring Okinawan purple sweet potatoes simmered in a savory miso broth, offering a colorful twist on a Japanese classic. This Japanese soup recipe (vegetarian), ready in about 30 minutes, pairs purple sweet potato, dashi stock, and white miso paste for a weeknight-friendly dinner that comes together with one pan and minimal cleanup. Each serving lands at about 150 calories and feeds 3, so it slots cleanly into a weekly meal plan and pairs well with a quick salad or grain on the side. Tap "Build a week of meals around this recipe" below to drop this recipe into your week and send the ingredients straight to Instacart. Nutrition values are approximate, calculated from USDA FoodData Central (fdc.nal.usda.gov) — verify against ingredient labels for any health-driven dietary plan.

Ingredients

• 200 g purple sweet potato, peeled and diced
• 4 cups dashi stock
• 3 tbsp white miso paste
• 100 g silken tofu, cubed
• 1 tbsp dried wakame seaweed
• 1 stalk green onion, thinly sliced

The stock pot we’d simmer this in → Best Stock Pots for 2026: Top Picks + Buying Guide

Instructions

1. Step 1: Peel and dice 200 g purple sweet potato into 1/2-inch cubes. Soak 1 tbsp dried wakame seaweed in cold water for 5 minutes to rehydrate.
2. Step 2: In a medium saucepan, bring 4 cups dashi stock to a gentle boil over medium heat. Add the diced sweet potatoes and simmer for 12-15 minutes until tender.
3. Step 3: Lower heat to low and whisk 3 tbsp white miso paste with a ladle of hot broth in a small bowl until smooth. Stir this miso mixture back into the pot gently, avoiding boiling to preserve flavor.
4. Step 4: Add 100 g silken tofu cut into cubes and the soaked wakame seaweed to the soup. Heat through for 2-3 minutes.
5. Step 5: Remove from heat and garnish with 1 thinly sliced green onion stalk before serving warm.