Meanwhile, make the sauce. Combine the oil, garlic, and red pepper flakes, in a large skillet. Cook over low heat, stirring often, just until the garlic begins to brown, about 3 minutes. Add the mushrooms and increase the heat to medium. Cook until the mushrooms exude their juices, about 12 – 15 minutes more. Stir in the broccoli rabe and dry oregano. Add water and soy sauce; cover partially with the lid. Cook, stirring occasionally, until the broccoli rabe is barely tender, about 5 minutes. Stir in the fresh oregano and season with salt and pepper. Keep warm.