Combine mayonnaise, anchovy paste, lemon juice and garlic. On a plate, combine crushed crouton crumbs and parmesan cheese. Spread the mayonnaise mixture completely over the tenderloin and then roll in the crumb/cheese mixture to coat. Place on a flat baking sheet.
Bake for 15-20 minutes or until tenderloin is medium well done (slightly pink in the center). Cut into 1/4 inch thick slices to serve.
Note: You can use a knife to spread the mayonnaise mixture on the tenderloin but I always use my hands to get it all over the place. It's messy but it seems to pay off. This is what those disposable gloves are for.
When I buy my pork tenderloin there are usually two in the package.
You find the anchovy paste in a tube like toothpaste near the tuna in the grocery store.
Put the croutons in a zip top plastic bag and use a rolling pin to crush them. It keeps them together and works great. You can add the parmesan cheese to this and mix it together well before you put the mixture on the plate.