In a large bowl, whisk together fresh lemon juice, minced garlic, salt, black pepper, and optional chili flakes. Slowly drizzle in olive oil while whisking to create a smooth emulsion.

Rinse lentils under cold water. Combine with a bay leaf and enough water to cover by an inch in a medium pot. Bring to a boil, then reduce to a simmer and cook for 20-25 minutes until tender. Drain excess water.

Add warm lentils to the bowl with the dressing, stirring gently to coat. Let cool slightly.

Chop cucumber, bell peppers, and green onions. Once lentils are cool, fold in chopped veggies, parsley, and mint. Toss gently.

Taste and adjust seasoning with more salt, pepper, or lemon juice. Refrigerate if desired, then serve.