For the salad, rinse lettuce well, pat dry and tear into pieces.
Heat oil in a heavy skillet, add steak slices and cook for 1 minute on each side. Reduce heat and cook steak slices for 2 to 4 more minutes per side, depending on final temperature preference.
Sprinkle steaks with salt, remove from pan and wrap in aluminum foil.
For the vinaigrette, mix all ingredients together.
Add lettuce to 4 plates and drizzle with vinaigrette.
Cut steak as desired and place on top of salads. Sprinkle with croutons if desired and serve.