We had drinks and then ate at Papillon twice during our time in St Cyr. The service was lovely,…read morevery friendly and caring. They also have a kids menu (although very limited selection... steak haché with either fries or pasta.. a drink and ice cream ... 9 euros). I wish they added a few veggies to that.
I had the salmon tartare one evening (really nice portion and yummy). And i tried the "tartare poêlé" the second time. I prefer the regular steak tartare but that's me.
Every dish came with fries and salad. Reasonable prices. A glass of wine is about 3,5-4 euros. Same for Pastis ;)
The service and the location made it a really nice spot to have dinner at. Highly recommend.