For a spicier dressing, add a pinch of red pepper flakes.
If you don't have a blender or food processor, you can finely chop the sardines and garlic and whisk them into the dressing with the other ingredients.
To make this salad ahead of time, prepare the dressing and croutons ahead of time. Store them in the refrigerator until ready to assemble the salad.
You can also use grilled chicken or shrimp instead of chicken tenders.