Ratatouille (/ˌrætəˈtuːiː/ rat-ə-TOO-ee; French: [ʁataˈtuj]) is a traditional French Provençal stewed vegetable dish, originating in Nice. The full name of the dish is ratatouille niçoise.[1]

Origin
The word ratatouille comes from Occitan ratatolha and the recipe comes from Occitan cuisine. Ratatouille originated in the area around present day Occitan Provença (French: Provence) and Niça (French: Nice); the Catalan samfaina and the Majorcan tombet are versions of the same dish.[2] The southern Italian ciambotta is a related spring vegetable dish.
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Piperade Mixture/ Sauce:
 1 Onion chopped
 2 Carrots unpeeled and grated 
4 Celery sticks 
1 Tablespoons Minced garlic 
1 Red bell pepper Charred, peeled, seeds and ribs removed 
1 yellow bell pepper charred, peeled , seeds and ribs removed 
2 Red chillies charred, peeled, seeds and ribs removed. (Optional) 
850 grams tomato sauce
2-3 Tablespoons Olive oil 
6 Fresh basil leaves. 
Salt and Pepper to taste

Vegetables:  
2 Zucchinis sliced 
2 Japanese or Chinese eggplants sliced 
6 Roma tomatoes sliced 

Procedure for the piperade mixture: 
1. Saute the onion with the olive oil until translucent ( do not brown). Add the celery, carrots, garlic and continue to saute until softened. 
2. Mix in the bell peppers,chillies and the can tomatoes.
Add salt and pepper to taste. Cook the mixture until the water from the tomatoes is evaporated. Add the basil leaves. Set aside
3. In a blender, blend the whole mixture into a thick sauce. Pour the mixture into a large pan (oven proof) / casserole dish. 

To Assemble the ratatouille:
4. Take a slice of each vegetable, put them together and stick them half way in the sauce 
5. Repeat the process and arrange the vegetables all over the pan in a circular or preferred design. 

6. Finally, drizzle some olive oil on top, salt, pepper and some dried herbs (basil, oregano and thyme). Cover with an aluminium foil. 
7. Bake it in the oven (300 F for about 2 hours). Remove the foil and bake for 45 minutes at 350 F to caramelize. Serve and Enjoy.