Make the crema.

In a medium bowl, whisk together the sour cream, lime juice, lime zest, salt, and cayenne until fully combined.  Cover the bowl tightly and chill until ready to serve.

For the avocado fingers:

Peel and remove the seed from the avocados and slice them into ½-inch slices.

Squeeze the limes over both sides of the avocados to keep them from turning brown.

In a small bowl, stir together the flour, chili powder, cumin, and salt.

In another bowl, combine the cornflour and bread crumbs.

Finally, in a third bowl, beat the eggs.

Dredge each avocado slice into the flour mixture, then the egg mixture, and roll in the breadcrumb mixture.  Set aside on a plate.

Repeat with the remaining avocado slices.

In a large, deep skillet over medium-high heat, heat the oil until shimmering.

Add the avocado slices in a single layer.  Cook for 3-4 minutes and then carefully turn with a spatula.  Cook on the other side for another 3-4 minutes.

Remove to a paper towel-lined plate.

Repeat the process with the remaining slices.

Sprinkle the avocado slices with another ½ teaspoon of salt.

Serve with the Spicy Lime Crema.