If the recipe calls for red, can I use white?
It really depends on the dish. Red is a more earthy flavor for more autumn and winter dishes. White is more spring and summer.
Personally I like miso soup with red miso.
Is there a particular recipe you plan on using?
Yes, the recipe is udon, creamy roasted kabocha squash, shitakes and a light miso broth. I think the red would probably be best, right?
Yes, with the squash for a autumn dish the red balances; it all depends on your tastes and somewhat the season.
If white is all you have try it. If's it's still warm where you are it could work well--maybe up the soy-sauce in the recipe, and/or grind up some toasted sesame seed, or use toasted sesame oil to make up for the strong flavor of the red and balance the sweetness of the squash.
But consider red is good to have to hand, it keeps 'years' in the fridge. "Miso Masters" is a excellent brand which is made in the US.
Thanks! I had no idea about the seasons thing with red and white.