Preheat your oven to 400°F (200°C).
In a large mixing bowl, toss the diced red bell pepper, chopped zucchini, diced carrot, sliced onion, and minced garlic with olive oil, salt, and pepper.
Spread the vegetables on a baking sheet in a single layer.
Place in the oven and roast for about 25 minutes or until the vegetables are tender and slightly charred.
While the vegetables are roasting, rinse the lentils under cold water and drain.
In a medium pot, bring 4 cups of water to a boil. Add the lentils and cook for about 20 minutes or until tender but not mushy.
Drain any excess water from the lentils and transfer them to a large mixing bowl.
Once the veggies are done roasting, add them to the bowl with lentils.
Toss the salad with dried oregano and lemon juice. Adjust the salt and pepper according to taste.