There are many places to eat outside in Beijing. Here is a list of some of them:

Vineyard Cafe

31 Wu Dao Ying Hutong, Dong Cheng District  
T: 6402 7961
www.vineyardcafe.cn

Courtyard restaurant and bar located near the Lama temple serving
delicious european home-style cooking. Great Pizzas, Pasta, Salads,
Soup, Seafood & Weekend Brunch. Extensive wine, beer and cocktail
selection. Lunch deals and free wireless internet. Home delivery &
takeaway.
H: 11.30am - 3.30pm, 5.30 - 10.30

Lotus Lane and Capital Garden are other good choices with outdoor seating.