Głodomory (Big Eaters in Polish) is a modern restaurant serving very good Polish food. If you are a foodie (but more of a meat foodie), check their splendid Polish dishes like Schabowy (pork chop) or klopsiki (meatballs). Also, their menu varies daily to offer additional dishes such as gulash so make sure you study the menu carefully.
They opened their summer garden just at the beginning of May. The location could be a bit better, as you are sitting in ul. Gagarina, but still there’s the district’s green surrounding you. I highly recommend it.
Głodomory is a splendid option before starting off for a stroll in the Royal Łazienki Park or a concert there, or in the many parks of Mokotów district (Morskie Oko and Park Dreszera are just 15 minutes walk from here). You might also want to finish your trip here as they have lots of desserts and drinks.