Bake or fry fillet fingers according to the package instructions.
Dice mango and cucumber finely and add them to a small bowl.
Mince cilantro and add it to the bowl. Add honey, lime juice and chili powder to the cucumber and mango as well. Mix well, until all evenly combined. Set aside.
In a small bowl, combine sour cream, heavy cream, minced cilantro, mashed avocado, salt, and garlic powder. Mix well and transfer into a small zip-lock bag.
To put together the tacos: add about a table spoon of relish to each taco. Then, add two fish fingers to each taco. Top off with some more relish and a couple of avocado slides. Cut a small tip off the bottom corner of the zip-lock bag and drizzle crema over tacos.