Albondigas or Caldo de Albondigas is one of the most traditional and delicious Mexican soups. In case you don't know, "albondigas" means "meatballs" in Spanish, and so this is a yummy meatball soup that is hearty and packed with wonderful vegetables.
Place ground beef in large mixing bowl. Add rice, 1/4 cup chopped onion, salt, pepper, cumin seed, and egg and mix until fully combined. Form meatballs about the size of a golf ball and set aside.
Heat large saucepan over medium high heat. Coat bottom of pan with approx. 2 Tbsp. oil. Once heated, add in remaining chopped onions and sauté until translucent. Add in chopped tomatoes and celery and allow to cook down a few minutes. Add in minced garlic and sauté. Add broth. Stir and bring to a boil. When it boils, carefully add in meatballs and lower heat to a simmer. Meatballs will take a total of 30 minutes to cook. (You will gradually add in other vegetables based on how long they take to cook.) 15 minutes after adding meatballs, add in potatoes and carrots. 7 minutes later, add in squash. Squash will take about 8 minutes to cook, which should bring you right up to 30 minute mark from the time meatballs were put in. Taste broth for salt and add desired amount. Remove from heat and let sit covered 5 minutes more before serving.