For the avocado-lime sauce: In a blender on low speed, mix the avocado, lime juice, 2 tablespoons water, sour cream, hot sauce and some salt. Blend until smooth. Set aside.
For the fish tacos: In a shallow bowl, mix the coriander, cumin, chili powder, garlic powder, salt, coffee, brown sugar and cornmeal until well combined. In another shallow bowl, whisk the eggs and hot sauce together.
Shred the cabbage as finely as possible, and slice the radishes as thinly as possible. Set aside.
Pour the oil into a large saute pan and heat over medium-high heat.
Cut the fish into 12 sticks, approximately 3 ounces each. Roll each piece of fish in the egg mixture and then coat well in the cornmeal mixture.
In batches, place the breaded fish into the hot oil, taking care not to overcrowd the pan. Brown the fish on each side, approximately 1 minute per side. Drain on paper towels, sprinkling the fish with a little salt as it comes out of the pan.
In a separate saute pan, heat the tortillas over high heat to brown slightly.
Place a piece of fish on each tortilla, and top with shredded cabbage, avocado sauce and radish slices.