TOSS: Use a mandoline to finely slice the red cabbage, fennel and red onion. Add the sliced vegetables to a mixing bowl, along with the oil, lime juice and apple cider vinegar (if using). Toss to coat the vegetables evenly in the dressing. Taste and add salt, if you like.
REDUCE: Add the orange juice, ground ginger, oregano, garlic powder and salt to a skillet over medium heat. Bring the juice to a gently bubbling simmer, stirring the seasonings to combine evenly. Simmer until the seasoning mixture reduces down until it’s thick enough to pull a clear path through it in the skillet with a spoon. It will look too thick at this point, but that’s ok, because the shrimp will release some additional liquid as they cook.
COOK: Add the shrimp to the skillet, tossing them to coat in the seasoning mixture. Cook, stirring often, until the shrimp are opaque, fully cooked through and glossy. Remove from the heat.
BLEND: Add all of the avocado cilantro cream ingredients to the blending container of your immersion blender, or a high sided narrow jar. Use an immersion blender to puree until you have a smooth, cilantro-flecked cream.
ASSEMBLE: Pile each tortilla with some of the slaw mixture, then top with the spicy orange shrimp. Spoon or drizzle each taco with some of the avocado cream and serve immediately.