Prepare the hearts- Rinse, trim excess fat or vessels, and pat dry. Drying helps them brown instead of steam.
Season- Toss the hearts with smoked paprika, black pepper, and a pinch of salt.
Sear- Heat olive oil in a hot pan. Add duck hearts in a single layer and cook for about 2–3 minutes per side until browned but still tender inside.
Build flavour- Lower heat, add butter and garlic, and stir for 1 minute. Add soy sauce and lemon juice, tossing to coat.
Finish- Sprinkle parsley over the top and serve immediately. They should be tender, slightly pink in the centre, and rich with garlic-butter flavour.