Kefir is made with dairy but it is a cultured product. From what I have read it is not as mucous forming and what little mucous it does produce is thinner and cleaner than what the regular mucous forming foods produce. Kefir can be made with just about anything and sometimes you'll find it made form coconut milk at the healthfood stores.
Many of us around here have used it post MC no probs. My daily morning drink is a concoction I made up after my current 35 day MC I just finished at the end of Dec. I make it using Kefir and it consists consists of 8 oz apple juice 4 oz Kefir (strawberry or peach or rasberry) one scoop of a green powder called Greens Plus 1 oz hemp oil and one tbsl of raw Cacao nibs that I grind to a powder in my coffee mill. I am bonkers over this new concoction both cause I love the taste and cause it packs a serious nutritional wallop along with a probiotics and some balanced essential fatty acids. Sometimes I'll skip dinner and have another one.
Cacao is the nut they make chocolate from and they have found that it is a very complex and super nutritious food made up of like 300 different elements and is also chock full of antioxidants. Unfortunately when they cook it and add all the dairy and sugar and whatever to make it into that we know as chocolate it that destroys most of the nutritional and antioxidant properties it contains in the raw state.