Put the potatoes in a pot, cover with water and bring to a boil over medium heat. Salt the water and cook until the potatoes are tender.

Drain the potatoes and set aside.

In a large saucepan over medium heat. Add the oil, onion, garlic and cook, stirring occasionally, until the onion begins to soften, about 1 minute.

Add the spinach and red pepper flakes and cook, about 3 minutes. Add the potatoes, salt and lemon juice.

Stir and cook about 5 minutes more. Season with salt and pepper. Serve warm