Heat olive oil in a large skillet over medium heat. Add the diced bell pepper, green beans, and red onion. Cook until the vegetables become tender but still maintain a slight bite.
Season the vegetables with salt and black pepper while cooking. Once softened, transfer them to a bowl and allow them to cool slightly before assembling the salad.
In a small bowl, combine olive oil, fresh lemon juice, Dijon mustard, cumin, salt, and black pepper. Whisk thoroughly until the mixture becomes smooth and well blended.
Stir in the freshly chopped dill. The dill adds a fresh, aromatic flavor that makes the dressing stand out.
Place the drained lentils into a large mixing bowl. Add the sautéed vegetables and pour the prepared dressing over the mixture.
Gently toss everything together to ensure the lentils absorb the flavorful dressing. This helps distribute the herbs and seasonings evenly.
Sprinkle most of the crumbled feta cheese into the salad. Fold it in gently to avoid breaking it down too much.
Reserve a small amount of feta for garnish if desired. The creamy, salty cheese perfectly complements the earthy lentils.
Serve the salad immediately while slightly warm or refrigerate it for later. The flavors continue to develop as the salad rests.
Before serving, garnish with extra dill, a squeeze of lemon juice, or a light drizzle of olive oil for added freshness.