Mix the slaw ingredients in a large bowl and cover for at least 1 hour. Strain the mixture in a colander to remove excess juice. While the slaw is sitting, blend the crema ingredients in a blender until creamy and set aside in airtight container. For the tempeh marinade, whisk the ingredients together and add thin slices (1/4 inch) of tempeh, making sure to coat both sides. Let sit for 10 min then add the marinade and tempeh to a cast iron skillet and grill for 2 to 3 minutes or until the edges caramelize, making sure to flip the tempeh half way through. Sear the tortillas in the skillet for 30 seconds and then assemble your delicious vegan taco!