Release pressure carefully using the quick-release method according to manufacturer's instructions, about 5 minutes. Remove chicken breasts and shred with 2 forks. Return shredded chicken to the pot. Add remaining onion mixture, chopped bacon, and sesame oil. Season with salt and pepper. Select the soup setting and add remaining chicken broth, 1/4 cup at a time (up to 1 1/2 cups), if desired. Simmer briefly until desired consistency is reached. (Pressure release time: 5 minutes, Simmer time: 5 minutes)