Large masa flatbreads topped with tangy tomatillo salsa and fresh garnishes are a street food staple. This family-friendly, vegetarian-adaptable dish is a fresh, healthy, and satisfying snack.
Combine masa harina, water, and salt in a mixing bowl; knead until the dough is smooth and pliable (about 3 minutes), adjusting water if needed.
Divide dough into 4 pieces. Shape each into an oval (about 7 inches long), pressing to about 1/3 inch thick; keep portions covered with a towel to prevent drying.
Preheat a large nonstick or cast iron skillet over medium-high heat. Cook each masa oval for 2–3 minutes per side until lightly golden and cooked through.
Remove from pan. Carefully slice open each oval lengthwise (like a pita), spread a thin layer of refried beans inside, and lightly press to seal.
Heat 1 tbsp vegetable oil in the skillet over medium heat. Fry bean-filled huaraches for 1–2 minutes per side until golden spots form. Drain on paper towels.
For salsa verde, simmer tomatillos and jalapeño in water for about 6 minutes until just fork-tender. Drain and blend with 1/2 cup onion, cilantro, lime juice, and salt until smooth.
Spoon warm salsa verde generously over each huarache. Top with crumbled queso fresco, sliced avocado, extra cilantro, and onions if desired. Serve immediately.