In a large mixing bowl, whisk together fresh lemon juice, minced garlic, salt, black pepper, and optional chili flakes until well combined. Slowly drizzle in extra-virgin olive oil while whisking.

Rinse lentils under cold water. In a saucepan, add lentils with water, cover, and bring to a gentle boil. Reduce heat and cook for 20-25 minutes until tender but firm. Drain and cool slightly.

Gently fold warm lentils into dressing. Incorporate cucumber, bell peppers, green onions, parsley, and mint. Toss gently.

Taste and adjust seasoning with lemon juice, salt, and black pepper if needed.

Serve immediately or chill to enhance flavors. Store in an airtight container for up to three days.