Boil eggs; allow to cool, then peel. Scoop avocado from the skin.

Add the first 7 ingredients (through chives) to a food processor and pulse a few times to combine, scraping the bowl once or twice if necessary. Continue pulsing until salad reaches the desired consistency, adjusting the seasoning as necessary.

Spread mustard onto bread, then add avocado mixture and spinach, forming 4 sandwiches.

Slice sandwiches in half if desired; serve with fruit on the side.