Beef Stir-fry with Pineapple and Bell Pepper

For this stir-fry, I used a package of pre-cut beef round stir-fry meat that I seasoned with some salt and pepper. I added a sliced white onion, a sliced red bell pepper, and a sliced orange bell pepper. I added in 8 ounces of canned pineapple chunks, and added the juice to ½ cup chicken stock, ¼ cup soy sauce and 1 tablespoon cornstarch. I whisked it together and added it to the stir-fry and let it cook down. I served it over rice and topped it with some toasted sesame seeds.