Start by cutting the onions into strips, transfer them to a bowl and add the sugar, mix very well until sugar has incorporated into the onions.
Into the bowl, add enough water to cover the onions, mix and set aside, let it marinate for 1 hour.
Cut the meat of your choice, start by cutting into thicker slices and then cut the slices in half, season with salt, black pepper, chimichurri, sweet paprika and oregano, mix very well with your hands until spices have incorporated into the meat.
After the indicated time, drain the water from the onions, transfer them to a dry bowl and add the vegetable oil, mix well.
Now, transfer onions to an oven bag, making a base for the meat, then transfer the meat to the bag, spreading it over the onions.
Close the bag and take it to a baking dish. Poke holes all over the bag with a toothpick.
Take baking dish to a preheated oven at 200°C (392°F) for about 90 minutes. Baking time may vary depending on the power of your oven
Cut open the oven bag to release the hot steam.