Go international for lunch
It’s worth seeking out the Marché des Enfants Rouges off rue de Bretagne in the Upper Marais: this old, covered market houses a mix of international cuisines, including North African, Italian, and Caribbean food. Check out Chez Alain, where patience is rewarded with phenomenal crepes and sandwiches.
... or go for lunch with a view
Have a light lunch (maybe one of the excellent croque monsieurs) on top of the museum at Georges, soaking up the magnificent views of the city. You can take the external escalator -- akin to a hamster tube -- all the way to the top, where both indoor and outdoor seating is possible.