In a skillet, heat vegetable oil over medium-high heat. Add chopped onion and diced tomato, cooking until softened and fragrant, about 5-7 minutes. Remove from heat and cool.

Combine cooled sautéed veggies with lean ground beef, chopped mint, chopped cilantro, beaten egg, soft breadcrumbs, and salt and pepper in a mixing bowl. Mix until just combined and chill for 30 minutes.

Shape the mixture into small meatballs, about 1-1.5 inches in diameter. Place on a parchment-lined baking sheet, yielding around 20 meatballs.

Bring beef broth to a boil in a large pot. Once boiling, decrease the heat to medium-low and let it simmer.

Gently drop meatballs into the simmering broth and cook for about 10-12 minutes, until they float, indicating they're fully cooked.

Add diced huisquil and julienned carrot to the pot. Simmer for 5-7 minutes until vegetables are tender. Stir occasionally and adjust seasoning if necessary.