Yes, miso is a Scrabble word!
...and is worth 6 points in Scrabble, and 7 points in Words with Friends
miso
Noun
1. A thick paste made from fermented soybeans and barley or rice malt; used in Japanese cooking to make soups or sauces
What Scrabble words can I make with the letters in miso?
3 Letter Words
2 Letter Words