Kosher sports has a few stands- Here is some info from their website koshersportsinc.com;
Shea Stadium in Flushing, NY
Location: Loge Section 13; Mezzanine Section 14; Kitchen in Rightfield Food Court adjacent to Dunkin Donuts / Baskin Robbins
Menu: Abeles and Heymann All Beef Hot Dogs w/ Sauerkraut, Hamburgers, Oceanside Knish Factory Homemade Potato Knishes, Chicken Nuggets w/Fries (At Field Level Location Only), French Fries (At Field Level Location Only), Pretzels, Peanuts, Soda and Bottled Water
Davening: Middle of 7th in Food Court