Summarize the following:
Bring to a boil over high heat; reduce heat to low and simmer, partially, covered, until lentils are soft and falling apart, about 15 to 20 minutes.

Summary:
Heat oil in large, heavy-bottomed saucepan over medium heat. Add onion and cook, stirring about 5 minutes or until soft. Add garlic, carrots, black pepper, hot red pepper flakes, oregano and rosemary; cook, stirring, about 2 minutes more. Add lentils and stock. Add lemon juice, salt and pepper. Serve hot soup in shallow bowls sprinkled with feta and chopped parsley.