Heat oven to 400°F. Spread eggplant in even layer on baking sheet lined with parchment paper. Drizzle with olive oil and season with salt and pepper, to taste. Roast eggplant until golden brown, about 30 minutes.

Warm 2 tablespoons olive oil (or ghee) in heavy Dutch oven over medium-high heat. Add some zucchini, just what covers the bottom of the pot in one layer. Cook, stirring occasionally, until golden and tender-crisp, about 5 minutes. Season with salt and pepper at end of cooking, to taste. Transfer cooked zucchini to large colander set over bowl to catch drained liquid. Repeat with remaining zucchini and summer squash. Add olive oil between batches, if needed.

After zucchini and squash has been cooked and transferred to colander, follow same process to cook bell peppers in batches. Transfer cooked peppers to colander filled with zucchini. Add olive oil to pot, if needed.

Add chopped onions and cook until softened and golden brown, 5–10 minutes. Season onions with salt and pepper, to taste. Reduce heat to medium. Add olive oil to pot, if needed.

Stir in garlic, ginger, curry powder, smoked paprika, red pepper flakes and tomato paste. Stir to coat onions, and cook for 1 minute, or until fragrant.

Stir in crushed tomatoes, scraping up any browned bits in pan. Bring sauce to boil, then reduce heat and simmer. Add any accumulated liquid from cooked vegetables. Let sauce simmer uncovered until thickened and reduced by about half, about 15-20 minutes over medium heat. Season with salt and pepper, to taste.

Heat oven to 350°F. Return cooked zucchini, squash, peppers and roasted eggplant to pot. Stir into tomato sauce. Cover pot, leaving lid slightly ajar, and transfer to oven. Roast for 30 minutes, or until sauce has reduced to jam-like consistency.

Stir in lemon juice, butter, mint and cilantro. Serve warm or at room temperature.