Cut zucchini, onion and tomato into 1/8" pieces.*
Squeeze any excess liquid out of the zucchini and let tomatoes drain in a colander.
In a dutch oven or large, rimmed skillet, heat 1 Tbsp. oil over low heat.
Add onion and sauté about 15-20 minutes until softened and starting to caramelize. Remove oven from pan and set aside.
Add additional 1 Tbsp. oil and then sauté zucchini for about 20 minutes, stirring occasionally until it is cooked down and caramelized. Remove zucchini from skillet and set aside with onions.
Add last 1 Tbsp. of oil and once warm, add tomatoes and allow to cook down for 10-20 minutes until most liquid is evaporated (cooking time depends on how much liquid is in the tomatoes.
Once tomatoes have cooked down, add zucchini and onion back to pan with tomatoes. Add salt, pepper, cumin and sugar and cook together for about 10 - 15 minutes longer, stirring every minute or two until most liquid has boiled off.
Taste and adjust seasoning if needed. The flavor of this dish depends on the sweetness, saltiness, caramelized flavor and acidity flavors balancing well so taste and adjust spices if needed. Exact amounts needed will vary based on sweetness/acidity of vegetables and how caramelized they get.
Serve with crackers and enjoy either warm or chilled. Dip will keep in the refrigerator in a sealed container for about 5 days.