Add the chicken broth, chicken, minced/crushed garlic, and brown rice to a large pot. Bring to a boil over medium-high heat, then reduce to a simmer, cover, and simmer for 35-45 minutes, or until both the rice and the chicken are fully cooked – the rice should be tender and the chicken should be cooked through, with no pink in the middle when you cut into it.
Remove the chicken from the pot and place on a cutting board. When cool enough to handle, tear into bite-sized pieces, and set aside.
Beat the egg white with a whisk in a medium bowl until it is white and thick. Lightly beat the egg yolk, then add the egg yolk to the beaten egg white and whisk together. Slowly pour the lemon juice into the egg mixture as you whisk. The mixture should be pale yellow and fairly thick. Slowly add a thin stream of the hot broth-rice mixture to the egg-lemon mixture, whisking the eggs vigorously as you do so, to temper the eggs.
Add the egg-lemon mixture to the pot with the broth, rice, and chicken. Stir to combine. Heat gently; do not boil. Season with salt and pepper to taste. Garnish with dill and serve.