- Cut the fennel heads in half length-wise. We use a mandolin slicer, but a sharp knife works as well. Slice into very thin strips and place in a mixing bowl.
- Cut and peel the onion and slice the same way as the fennel.
- 3.Take the fennel and onion mixture and combine with the juice of one lime, minced cilantro, and a pinch of salt and toss to combine. Set aside until the assembly of the tacos.
- Puree the crema or sour cream, mayonnaise, salt, lime juice, and 3−5 chipotle peppers (depending on how spicy you like it) in a blender until smooth. Check for spice level and adjust with peppers if you like. Set aside until time to assemble the tacos.
- Combine ingredients.
- Dip oysters in the buttermilk and let excess drip off as you transfer them to a bowl with the flour mixture. Dredge the oysters, thoroughly coating them with the flour mixture, and transfer to a plate until ready to fry them.
- In a cast iron skillet heat the oil to 350 degrees and add 8 oysters at a time. Fry until golden brown and transfer to a paper-lined plate while you fry the rest of the oysters.
- While the oysters are frying, heat the tortillas in an ungreased pan until hot and wrap in a dishtowel to keep warm and steam.
- When all the oysters are ready you can begin making the tacos. Start with a warm tortilla. Spread about 1 tablespoon of the chipotle crema over it and place 3 fried oysters on the tortilla. Top the oysters with about 2 tablespoons of the fennel slaw and 2 slices of the radish. Repeat until all the oysters are gone.