Start the skillet: Set a large skillet with a lid over medium heat.

Add the olive oil to the skillet and heat it for about 30 seconds, until it looks loose and glossy.

Add the chopped onion and the kosher salt to the skillet. Cook for 4 to 5 minutes, stirring a few times, until the onion softens and starts to look translucent.

Add the sliced garlic and red pepper flakes to the skillet. Stir for 30 seconds, just until the garlic smells fragrant.

Put the drained lentils into the skillet and stir in the dried oregano.

Pour the water into the skillet. Squeeze in the juice from one lemon half and stir everything together.

Let the lentils simmer for 3 to 4 minutes, stirring once or twice, until the liquid reduces a little and the mixture looks moist and lightly brothy instead of soupy.

Add the spinach to the skillet a handful at a time. Stir after each handful so it wilts down before you add more.

Sprinkle in the black pepper and taste the lentil mixture. Add a little more salt if it needs it.

Spread the lentils into an even layer across the skillet and lower the heat to medium-low.

Add the eggs: Use the back of a spoon to make 4 shallow wells in the lentil mixture.

Crack 1 egg into a small bowl, then slide it into 1 well. Repeat with the remaining eggs so the yolks stay whole and any shell pieces are easy to catch.