Estamboli Kuku (کوکو استانبولی) — Persian Potato and Bean Frittata

• 600 gYukon Gold potatoes, peeled and cut into 1 cm dice (Rinse briefly and pat very dry for better browning)
• 200 gYellow onion, finely diced (About 1 large onion)
• 240 gCooked beans (cannellini or pinto), drained and rinsed (About 1 1/2 cups; canned is fine)
• 2 tspGround turmeric (For color and warmth)
• 1.5 tspFine sea salt (Divide between potato mixture and egg batter)
• 0.75 tspBlack pepper, freshly ground (Adjust to taste)
• 6 pcsEggs, large (Room temperature helps even cooking)
• 60 mlWhole milk (About 1/4 cup; optional but makes a softer set)
• 120 gMozzarella cheese, shredded (low-moisture) (About 1 cup, lightly packed)
• 60 mlNeutral oil (sunflower, canola, or grapeseed) (About 1/4 cup, divided for frying and pan coating)

Instructions

1. 1

   Prepare the potatoes and onion: rinse the diced potatoes briefly, then dry thoroughly with towels so they fry instead of steaming. Heat a 26 cm (10-inch) nonstick skillet over medium-high heat for 2 minutes, then add 45 ml oil. Add potatoes and onion, spread into an even layer, and cook 12–15 minutes, stirring every 2–3 minutes, until the potatoes are golden and tender.

2. 2

   Season and add beans: reduce heat to medium. Sprinkle in turmeric, 1 teaspoon salt, and all the black pepper, then stir for 30 seconds to bloom the turmeric in the hot oil. Add the drained beans and cook 2 minutes, gently folding so the beans warm through without breaking too much. Transfer the mixture to a bowl and cool 5 minutes so it does not scramble the eggs.

3. 3

   Make the egg batter: in a large bowl, whisk the eggs with the milk and remaining 1/2 teaspoon salt for 30–45 seconds until uniform and slightly frothy. Fold in the cooled potato-bean mixture until evenly coated. Wipe the skillet clean, return it to medium heat, and add the remaining 15 ml oil, swirling to coat the base and sides.

4. 4

   Cook the kuku: pour the mixture into the skillet and press gently into an even thickness. Cover with a lid and cook on medium-low for 12–14 minutes, until the edges are set and the center is mostly set but still slightly glossy. Sprinkle mozzarella evenly over the top, cover again, and cook 3–4 minutes until the cheese melts.

5. 5

   Finish and serve: for a lightly browned top, place the skillet under a preheated broiler/grill on high for 1–2 minutes, watching constantly to prevent burning. Rest the kuku 5 minutes to firm up, then slide onto a board and cut into 8 wedges. Serve warm or at room temperature; the flavor deepens after a short rest.