Heat the olive oil over medium high heat in a heavy, 10” (25cm) lidded sauté pan.
Add the onions and potatoes, and cook until well browned, about 3-5 minutes.
Add the kale, garlic, salt and pepper, and the water. Cover the kale, and allow to simmer over medium heat for about 20 minutes, until the kale is tender.
Remove from heat, and drain the kale mixture in a colander, so that all the liquid drains away. Allow to cool completely.
Preheat the oven to 400°F (204°C)
Fill each of the discs with 1 generous tablespoon of kale filling. Pinch the edges together to seal.
Place the formed empanada on a greased cookie sheet. Form all the empanadas in the same fashion.