Place lentils in a pot on the stove and cover with about 2 inches of water. Bring to a boil and then reduce heat to simmer. Cook on low for about 25 to 30 minutes. Drain.
Heat olive oil in a pan on the stove over medium heat. Add in onions and stir occasionally for about 5 minutes. Then add in garlic, tomatoes, cucumber, cumin, ginger, paprika, cayenne and stir and continue to cook for about 3 minutes.
Add in the cooked lentils and stir for a minute. Finish with the lemon juice, salt and pepper.
Remove from heat and put into a large bowl. Stir in Feta cheese and serve warm.