Heat the first tablespoon of oil in a large nonstick skillet over medium-high heat until the oil shimmers. Add the poblanos, bell peppers, and salt, then cook until the vegetables are softened and charred in spots, about 8 to 10 minutes. Transfer the mixture to a bowl and wipe the skillet clean.

Whisk the masa harina and salt together in a medium bowl. Slowly stir in the hot tap water until a smooth, slightly tacky dough forms. Let the dough rest for 5 minutes — this allows the masa to fully hydrate so the cakes don't crack during shaping.

Divide the dough into 6 equal portions. Roll each portion into a 5-inch cylinder and flatten it into a 7-inch-long, 4-inch-wide oblong shape, about 1/4 inch thick. Keep the dough portions covered with a damp towel while you work.

Heat the remaining 2 tablespoons of oil in the skillet over medium heat. Cook the masa cakes in batches until they are deeply golden-brown and crisp on both sides, about 3 to 4 minutes per side.

Spread the warmed refried beans over each hot cake. Top with the sautéed pepper mixture, pickled shallots and radishes, and queso fresco. Serve immediately while the cakes are still warm and crisp.