In a large bowl, combine masa harina, salt, and warm water. Mix with your hands until a soft dough forms. Let rest for 10 minutes.
Divide the dough into 6 equal portions and roll each into a ball.
Place each ball between two sheets of plastic wrap or parchment paper and press into a 4-inch thick disc using a tortilla press or a heavy pan.
Heat a large skillet over medium heat and cook each disc for about 1 minute on each side until lightly cooked but not browned. Remove and let cool slightly.
Pinch the edges of each disc upward to form a raised border around the perimeter, creating a shallow bowl shape for the sope.
Heat 2 tablespoons vegetable oil in a skillet over medium-high heat. Fry each sope for about 2 minutes per side until golden and crispy. Drain on paper towels.
In another skillet, heat 1 tablespoon vegetable oil over medium heat. Add chopped onion and garlic; sauté for 2 minutes until softened.
Add shredded chicken, cumin, chili powder, paprika, black pepper, and salt. Stir to combine and cook for 5 minutes until heated through and well seasoned.
To assemble, spread about 2 tablespoons of warm refried beans on each sope.
Top with a generous portion of the seasoned shredded chicken.
Add shredded lettuce, crumbled queso fresco, a spoonful of salsa roja, and sprinkle with chopped cilantro.
Serve immediately while warm.