Combine olive oil, vinegar, mustard, pepper, and salt in a 1-pint mason jar with a lid; shake well to blend. Divide dressing between 2 (1-pint) mason jars.
Divide onion between the 2 jars. Repeat procedure with chickpeas, bell pepper, hearts of palm, tomatoes, protein and quinoa (if using quinoa).
Divide lettuce between the 2 jars, gently pressing down to fit. Divide cheese between the 2 jars; secure lids on jars.
Refrigerate salad up to 1 day. Shake jar to distribute dressing before serving. Eat straight from the jar, or empty contents into a bowl.