What is halal, what is haram?

The Qur’an defines eleven groups of causal impurities. Four of them relate to food.

Forbidden to you are carrion, blood, the flesh of swine, the animal slaughtered in any name other than Allah's, the animal which has either been strangled, killed by blows, has died of a fall, by goring or that devoured by a beast of prey - unless it be that which you yourselves might have slaughtered while it was still alive - and that which was slaughtered at the altars. […](Qur’an, 5:3)

Prohibited are:

• Carrion (all animals which have died from a natural death)
• Blood (just the blood which remains after proper slaughtering and bleeding in the animal may be consumed)
• Pig (all foods containing ingredients from pork)
• Slaughtered animals, that are ordained others than God as sacrificial animals of non-monotheistic religions)
• Alcohol

Forbidden are also carnivorous animals with fangs, birds of prey, poisonous animals and vermin.
Food made out of plants is generally halal except for food which is exhilarating and toxic, e.g. alcohol. Spices are not related to this.

Intoxicants, e.g. alcohol, are considered harmful. The consumption of those is even in small quantities is not permitted.

Believers! Intoxicants, games of chance, idolatrous sacrifices at altars, and divining arrows are all abominations, the handwork of Satan. So turn wholly away from it that you may attain to true success. (Quran 5:90)

To produce halal foods it must be ensured that all ingredients are halal and free from harmful substances.