The dish you saw in the film ratatouille is not a ratatouille. It's a Confit Byaldi:
https://en.wikipedia.org/wiki/Confit_byaldi
I personally much prefer ratatouille, even if the presentation is not as impressive.
Ratatouille is delicious hot or cold right out of the fridge. It's great alone and goes wonderfully with rice. Cold ratatouille with hot rice is a rare treat in the summer.
If you like meat, just serve meat along with it. A grilled pork chop, or some grilled sausages, roast or grilled chicken would go great with it.
Here are two recipes, one "fancy" and the other "quick", that I use. Use more olive oil than you think is necessary:
French Fries' Ratatouille
Serves many for several days
Eggplants 2 lbs
Zucchini 2 lbs
Red bell peppers 1 lbs
1 big onion finely minced
Tomatoes 2 lbs
Garlic to taste, crushed and minced
Bouquet garni with thyme, celery and fennel
All quantities are guidelines. Some people make ratatouille without eggplant. Or without zucchini. Or without pepper. Adjust the recipe to match the season, the market, and you and your family's taste.
1) Prep all veggies, dicing everything in about 1/2'' cubes.
2) Make the tomato fondue:
Sweat onion in a little olive oil. Add tomato, garlic and bouquet garni. Season, and if necessary, add sugar and or tomato paste. If you use good ripe tomatoes, it's not necessary. Cook on low heat until all the water from the tomatoes evaporates.
3) In a pan with a little olive oil, lightly saute the zucchini, giving them a light golden color, until almost cooked but still firm.
4) In another pan with a little olive oil, lightly saute the eggplant, light color, still firm.
5) In another pan with a little olive oil, lightly saute the bell peppers, keeping them a bit firm.
6) Add zucchini, eggplants and bell peppers to tomato fondue, gently mix and let cook very, very slowly for 15-20mn.
The result should be an amazing mix of vegetables that still have their individual identity, and still have some bite. All the flavors are layered. There shouldn't be much juice at all in the pan.
Note: Ratatouille is absolutely delicious served cold. In that case you can add black olives, capers, basil...
Now for the week nights:
French Fries' Quick Ratatouille
1) Lightly saute the onion in olive oil.
2) Add the bell peppers, lightly saute and let soften a bit.
3) Add the eggplant, lightly saute and let soften a bit.
4) Add the zucchini, lightly saute and let soften a bit.
5) Add the tomato and the bouquet garni, and let cook until all veggies are tender.
The result will be more mushy, more juicy than the first recipe. It will be more "one taste", with no layers of flavors, and veggies most likely wont' have a bite to them. This is quite good served with white rice to mop up the juices. But nowhere near as good as the first recipe.
Tip: If you like the taste of garlic, reserve some of the minced garlic and add it 5-10mn before the end of the cooking.