Make Kefir Cream (Optional-- uncultured heavy cream works fine)
In a pint-sized jar, add 12 ounces heavy cream and 1/4 cup finished milk kefir. Stir occasionally. Wait 24-48 hours, or until cream thickens and tastes sour. See full recipe.
Prepare & Chill Base
Add eggs and honey to a 3 quart or larger pitcher or mixing bowl with a pouring spout. Beat until incorporated.
If using vanilla beans, split beans lengthwise, and scrape out the insides into mixing bowl. Add long bean pod pieces (3" or longer) to mixing bowl. If not, add vanilla extract.
Add kefir, cream or kefir cream, salt, and lemon zest to pitcher/bowl. Whisk to combine.
Place mixture in refrigerator to chill overnight or up to 8 hours.
Make Ice Cream
Fish out vanilla bean pods from mixture.
Whisk ingredients together (settling may have occurred during chilling).
Follow machine instructions for making ice cream. Be careful not to overfill the machine, otherwise it may overflow or not freeze properly.
When mixture has aerated and resembles soft-serve ice cream (usually 15 to 20 minutes for most machines), add the mix-ins. Let machine run a few more minutes.