Heat a heavy-bottomed pot over medium heat and add the olive oil, listening for a gentle sizzle.
Add the diced onion and minced garlic to the pot, sautéing until fragrant and translucent, about 3-4 minutes. The aroma should turn sweet and pungent as they soften.
Stir in the diced chicken and cook until the edges turn white, about 5 minutes, breaking up the pieces slightly as they cook through.
Sprinkle in chili flakes or chopped fresh chilies, stirring well to coat the chicken and vegetables, filling the air with a spicy aroma.
Pour in the broth, scraping any browned bits from the bottom of the pot for extra flavor. Bring the mixture to a gentle simmer.
Reduce the heat to low and let the soup simmer gently for about 20 minutes, stirring occasionally, until the chicken is tender and flavors meld together.
Taste the broth and add a squeeze of fresh lime juice, adjusting the spice level with more chili if desired. Stir to combine.
Ladle the steaming hot soup into bowls, garnishing generously with chopped cilantro or parsley for a burst of freshness.
Serve immediately, enjoying the bold, spicy aroma and the tender chicken pieces floating in the vibrant broth.