A comforting Sonoran soup of potatoes, roasted green chiles, and melting cheese in a milk broth. This vegetarian, protein-rich family comfort food is unique to northern Mexico.
Heat olive oil in a large pot over medium heat. Add diced onion and sauté for 3–4 minutes until translucent, then stir in minced garlic and cook 1 minute until fragrant.
Add peeled and diced potatoes, season with 1 tsp salt, and toss for 2 minutes to coat. Pour in water and add bay leaf. Bring to a simmer over medium-high heat, then reduce heat to low, cover, and gently simmer for 15–18 minutes until potatoes are just tender.
Stir in the roasted green chiles. Raise heat to medium and cook uncovered for 3 minutes for flavors to meld.
Lower heat to low and gradually pour in milk, stirring constantly. Bring just below a simmer — do not boil — and cook for 5 minutes to heat the broth through.
Remove the bay leaf. Gently stir in cubed cheese, keeping the heat low so the cheese softens but does not fully melt or dissolve. Season with remaining salt and black pepper to taste, then serve immediately while cheese is creamy and semi-melted.