Put lentils, 4 cups water and bay leaf into a medium pot and bring to a boil. 

Reduce heat to medium-low and simmer, covered, until lentils are tender but not mushy, 30 to 35 minutes. 

Remove from the heat and set aside to let cool; discard bay leaf and drain lentils well.

Meanwhile, heat 1 tablespoon of the oil in a medium saucepot over medium heat. 

Add kasha, shallot and garlic and cook, stirring occasionally, until shallot is softened, 3 to 4 minutes. 

Add 1 cup water and bring to a boil. 

Reduce heat to medium-low and simmer, covered, until water is almost absorbed and kasha is almost tender, about 5 minutes. 

Quickly add oregano, recover pot and continue to simmer until liquid is completely absorbed, 3 to 4 minutes more. 

Remove from heat and set aside, uncovered, to let cool.

Put lentils, kasha mixture, tomatoes, olives, green onions, parsley, remaining 2 tablespoons oil, salt and pepper into a large bowl and toss gently to combine. 

Serve at room temperature or chilled, garnished with feta cheese.