Make the dressing: Whisk olive oil, lemon juice or vinegar, Dijon, honey, garlic, salt, and pepper until smooth. Taste and adjust acidity or sweetness.
Divide the dressing: Pour half the dressing into each clean quart-size mason jar, keeping it at the bottom.
Add hardy veggies first: Layer tomatoes, cucumber, bell pepper, and red onion directly on the dressing.
These can handle contact with liquid.
Add protein and grains: Spoon in chickpeas or chicken, then quinoa or brown rice. Press gently to create even layers.
Add extras: Sprinkle cheese, seeds or nuts, and herbs. Keep avocado out for now to avoid browning.
Top with greens: Pack in mixed greens or romaine to the top.
The greens should be far from the dressing.
Seal and chill: Screw on lids tightly. Store upright in the fridge for up to 4 days.
Serve: When ready to eat, add fresh avocado if using. Shake the jar hard to coat everything, or tip into a bowl and toss.