In a mixing bowl, combine chickpeas, red onion, Dijon mustard, parsley, capers, celery, tahini, salt and pepper. Mash until creamy with some chickpeas intact.

Taste and adjust seasoning as necessary. Set aside.

Spread chickpea salad on the bottom slice of bread.

Add fresh veggies on top of the chickpea filling.

Sprinkle lightly with salt and pepper before capping with the top slice of bread.

Cut in half and serve.

Store leftover filling in an airtight container for up to three days.