Layer the lettuce around a platter. Add layers of veggies.
Fill in with tuna or salmon. Add capers and olives
Drizzle dressing over the salad just before serving.
In a bowl, whisk Dijon, lemon juice, vinegar, olive oil, garlic, thyme, salt, pepper and anchovy paste or filet if using, until blending. Can be made ahead and stored in the refrigerator until ready to serve.