Heat 3 tablespoons oil in a large deep-sided skillet over medium-high heat. Add cubed eggplant; cook, stirring often, until starting to soften, about 3 minutes.
Add cubed zucchini, chopped onion, diced bell pepper and the remaining 2 tablespoons oil; cook, stirring often, until the vegetables are tender-crisp, about 6 minutes. Add minced garlic; cook, stirring constantly, until fragrant, about 30 seconds.
Stir in 2 tablespoons tomato paste; cook, stirring constantly, until it begins to darken, about 2 minutes. Add 2 cups broth, cubed tomato, 8 ounces precooked lentils, ½ teaspoon plus ⅛ teaspoon salt and ½ teaspoon pepper; bring to a gentle simmer over medium-high heat. Reduce heat to medium-low and cook, stirring occasionally, until the lentils are heated through and the sauce thickens slightly, about 10 minutes.
Remove from heat and stir in ¼ cup basil and 1 teaspoon oregano. Garnish with additional basil, if desired.
