Prepare the slaw first: Mix first 6 ingredients (cabbage through ground black pepper) in a large bowl (don't use metal). Cover and place in fridge. Weigh down slaw with canned beans or full pickle jar. Slaw improves the longer it's allowed to mellow. Allow to press for at least 1 hour. When ready to use, squeeze out handfuls to release any excess juice.
Make the lime cream: Blend ingredients from yogurt to 1/2 t salt in a blender until creamy and smooth. Add more salt or lime juice to taste, if desired. Pour into an airtight container and chill for 1 hour.
Make the marinade: Whisk together ingredients from beer to cumin and pour into a glass pie plate or casserole dish.
Prepare the Tempeh: Boil water in a 2 qt pot. Slice tempeh into 3 pieces lengthwise and then in half horizontally through the middle. Add the tempeh to the water, reduce heat to low and simmer for 10 minutes. Remove pieces with tongs and place directly in marinade dish. Marinate for 1 hour flipping occasionally to cover.
Preheat the oven to 200. Preheat a greased grill pan over medium-high heat.
Grill tempeh for 5 minutes on each side, while basting with marinade. Remove from heat and slice into thin strips. Keep warm, covered in foil in the oven while assembling tacos.
Heat a corn tortilla, spread lime crema down the center, top with slaw, tempeh and then any garnish you like (diced tomato, pickled jalepenos, hot sauce, avocado, lettuce, etc). Fold & eat.