Start by making the croutons. Cut the bread into pieces approximately 2 cm/¾ inch in size and toss with the olive oil, garlic and salt. Bake at 190℃/375℉ for 15 minutes (give them a stir halfway through) or until they are no longer soft inside otherwise they will taste hard instead of crispy when cooled.
Next make the dressing. Add the egg yolks, lemon juice, dijon mustard, 2 chopped anchovies, minced garlic, oil Parmesan cheese and a pinch of salt to a blender or food processor. Blend until smooth. Taste and add more salt if needed. The whisk in the water by hand to bring the dressing to the needed consistency. Set aside till needed.
Pat the salmon pieces dry with a paper towel, then season with salt, pepper and lemon zest from one lemon. You can cook the salmon in the air fryer, in a pan or an oven.
If cooking in the air fryer Preheat the air fryer to 200℃/400℉. While it's preheating, season the salmon with salt and pepper and sprinkle the zest of half a lemon all over. Once the air fryer is preheated, arrange the salmon in the basket of the air fryer and spray it with a cooking spray. (If you choose to use oil instead of the spray, brush the salmon with 1 tsp of olive oil, then season with salt, pepper and lemon zest.) Cook for 8 minutes.
If cooking in the oven, follow the instructions above but cook for 10 minutes.
If pan frying, heat 1 tbsp oil in a non-stick pan, then add the salmon to the pan skin side up and sear for 3-4 minutes over medium high heat until golden and crispy, then flip on the other side and cook for 3 minutes longer or until the sides change colour from orange to pale pink all the way through.
To assemble the salad separate the romain lettuce into individual leaves and wash well (dirt gets trapped between the leaves), then dry using a salad spinner or manually. If using romaine lettuce cut the leaves into smaller pieces but if using gem lettuces, leave them whole and add to a large bowl. Add the sliced cucumber and Caesar dressing to the lettuce and toss well to completely coat the vegetables. Sprinkle the croutons, top with cooked salmon and grate more Parmesan on top. Serve immediately.