In bokashi composting method you can use cooked food as well.
Following from the net:
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Now comes the fun part of having a worm bin -- feeding the little guys. You can bury just about anything that originally came out of the ground in the bin. Coffee grounds and filters, tea leaves and bags, fruit and veggie peels and cores, paper, rice, grits, and natural fabrics are all things that can go in the bin. Eggshells that have been washed out and ground up are also an excellent source of calcium for the worms.

The following items make good worm food:

Leafy greens
Potatoes
Non-acidic fruits and vegetables (tomatoes, green peppers)
Low-acidity citrus
Coffee & tea grounds
Rice
Grits
Paper
Cotton
Eggshells
There are also several items that will harm the worms. For one, don't feed them anything fatty or oily. Worms can't digest meat proteins or lactose, so no dairy products either, like milk or cheese. While worms do like egg shells, the egg cannot go in the bin. Citrus and salt can actually harm the skin of the worms. We mentioned earlier that worms breathe through their skin, so just imagine if your lungs were on the outside of your body and someone decided to rub salt and lemon on them -- you probably wouldn't appreciate it either.

These items will harm your worms. Never give them:

Butter
Oil
Salad containing salad dressing
Eggs
Meat
Highly acidic fruits and vegetables (lemons, limes, oranges)
Hot peppers
Salt
Animal waste
Plastic
Synthetic materials
Insecticides

INTERESTING ARTICLE I CAME ACROSS. ENJOY
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Eat My Shorts!

The Len Foote Hike Inn is a hotel in the North Georgia mountains that has an extensive vermicomposting system in the basement. With the help of the guests, they compost 1,500 pounds (680.4 kilograms) of food and office waste per year, and use the fertilizer in their organic gar�den. When the hotel staff gets bored, they find new (yet safe) things to shred and feed to the worms. One famous story tells of a pair of corduroy pants left by a guest that were never claimed. The staff shredded them up, buried them, and never saw them again. When sifting one day, an employee came across a button and a zipper � the rest had been eaten!

Thanks. I suppose it's ok to feed them boiled herbs (herbal medicine) then, since they were once plant material too.