For the dressing: Put the oil, vinegar, mayonnaise, mustard, garlic and a pinch of salt and pepper in a jar or blender. Add the water and shake or blend until smooth.
For the salad: In a 1-quart wide-mouth mason jar, layer: 1/4 cup of the dressing, the artichoke hearts, cucumber, olives, tomatoes, feta and chickpeas. Top with the chopped lettuce. Put the lid on the jar and store in the fridge for up to 2 days. Shake and eat straight from the jar.