Until recently, I treated this more like a one pot dish. However, by cooking ingredients individually, I like the layers of flavor that are developed.
Saute eggplant till soft, reserve.
Saute onion till slightly brown, add garlic, reserve.
Deglaze with a little soy sauce and olive oil and saute zucchini and squash, reserve.
Warm tomato paste in a splash of olive oil, add onion and stir well.
Add eggplant and zucchini.
Stir in crushed tomato, simmer to combine.
Add soy sauce, rice wine, rice wine vinegar and chili garlic paste to taste.