I made this soup for lunch over the weekend - it was very simple, very tasty, and only took a few minutes. I think you could substitute any firm white fish for the opah, and any sort of veg you particularly like. I definitely liked the play of color the carrots gave the soup, as well as the crunch and the flavor. (Click the picture for a full view.)
1 packet (2 oz) bean thread/glass noodles
1 packet (2 servings) instant dashi
1 tbsp yellow miso paste
0.5 lb opah, cut into 1-2 inch chunks
1 carrot, cut into half-inch thick slices
1 dash hot sauce
sushi sprinkle or shreds of seaweed for garnish (optional)
1. Put a pot of water on to boil. Cook bean thread noodles according to instructions. Drain them when done and set aside.
2. Dissolve the dashi in 2 cups of water. Add hot sauce to taste (this is for flavor, not for super heating the soup). Bring the broth to a simmer.
3. Turn down the heat, and add the fish. Poach gently for 4-5 minutes, or until the fish is done. Add the carrots in the last minute or so of cooking.
4. Divide the glass noodles into two bowls. Top with each bowl with half of the fish and carrots.
5. Stir the miso paste into the broth. Fill each bowl with broth. Top with sprinkle or seaweed, and serve!