Form meatball mixture into balls approximately 1/2 inch in diameter. You can also use a small ice cream scoop. The mixture should make about 35-40 mini meatballs.
Meanwhile, heat oil in a large pot or large Dutch oven over medium-high heat. Add onion, carrots, celery, and thyme. Cook until fragrant and starting to soften, about 3 to 4 minutes.
Add chicken broth and bring to a boil.
Add the barley and lower to a simmer for 25 minutes, stirring everyone once in a while to prevent the barley from sticking to the bottom of the pot.