Heat a large cast-iron frying pan over medium-high heat. Season meat with salt and pepper. Add 1 tbsp. oil to skillet, then add meat and brown in 2 batches, 2 to 3 minutes per side. Transfer to a plate.
Add remaining 1 tbsp. oil to frying pan, then add 3 thinly sliced green onions, garlic, and bell peppers; cook until lightly charred, 2 to 3 minutes. Add piquillos, Peppadews, Peppadew liquid, sherry vinegar, and smoked paprika and cook until liquid thickens, 4 minutes. Return meat to pan and cook 1 minute more. Divide among 4 plates and top with sliced green onion ends.