01 - Combine lentils, water, bay leaf, and 1/2 teaspoon salt in a saucepan. Bring to a boil over high heat, then reduce heat to low and simmer for 20 to 25 minutes until lentils are tender but still hold their shape. Drain well in a fine mesh strainer, discard the bay leaf, and spread lentils on a baking sheet to cool to room temperature.
02 - While lentils cool, halve the cherry tomatoes. Dice the cucumber into 1/2-inch pieces. Finely chop the red onion. Dice the roasted red pepper into small cubes. Slice the Kalamata olives into rings. Coarsely chop the fresh parsley and mint leaves.
03 - Whisk together the extra-virgin olive oil, lemon juice, dried oregano, Dijon mustard, minced garlic, 1/2 teaspoon salt, and black pepper in a small bowl or jar until fully emulsified and creamy.
04 - Transfer the cooled lentils to a large mixing bowl. Add the cherry tomatoes, cucumber, red onion, roasted red pepper, olives, parsley, and mint. Pour the dressing over the salad and toss gently to coat all ingredients evenly.
05 - Gently fold in the crumbled feta cheese, being careful not to break it up too much. Taste and adjust seasoning with additional salt and pepper if needed.
06 - Serve immediately at room temperature or refrigerate for at least 30 minutes to allow flavors to meld. This salad keeps well in an airtight container for up to 3 days.