Prep: 1. Mince garlic. 2. Grate cheese. 4. Tear lettuce leaves to bite sized pieces. Set aside in bowl. Make: 1. Add garlic and fish sauce (if using) to a bowl, then spoon in mustard, mayonnaise, vinegar and cold water. 2. Stir in half of cheese, season with salt and pepper, to taste. 3. Drizzle dressing over lettuce, toss, and serve topped with remaining cheese.
If you prefer you can use an anchovy fillet in place of the fish sauce, the fish sauce is technically optional but is what gives this dressing its traditional Caesar salad flavor.