Drain the soaked lentils and place in a saucepan. Add enough water to cover the lentils by an inch, and bring to a boil. Lower the heat to simmer. Let the lentils cook until they are perfectly tender but still holding their shape. This should take anywhere between 10-15 minutes.
Heat the oil in a large saucepan.
Add the onions, carrots and celery. Season with salt and pepper and saute for about five minutes or until the vegetables start to soften.
Add the mushrooms, plum tomatoes, oregano, paprika, cumin and cinnamon. Saute until the tomatoes start to soften, about five minutes.
Add the cooked, drained lentils with a cup of water or the cooking liquid. Bring the sauce to a boil, cover and cook for 10 more minutes over medium-low heat.
Add the cooked orzo pasta and parsley and stir well. Turn off the heat.
Serve hot, warm or cold. It's delicious every way.