Safe to eat (with mild reservations)
The following items are often listed on the internet as "toxic" to dogs, but as a vet in practice, I have never encountered instances where toxicity has actually happened. The potential toxic effect is more theoretical than real, but nonetheless, this aspect deserves to be mentioned. None of these items are likely to be used as "main dishes" for dogs, and their use as flavouring or as ingredients in sensible quantities is highly unlikely to cause toxicity issues. Preparing food for dogs is similar to cooking for humans in many ways: common sense ought to apply. Just as you would not prepare a hot chili dish for a five-year-old child who has never eaten curry, why would you ever do such a thing for a dog?
• Chili - While chili - and chili peppers - aren't specifically toxic to dogs, they both contain capsaicin which can act as an irritant to dogs if eaten in high quantities, causing gastrointestinal upset. But dogs do not generally like spicy food, and will not eat it. So again, it's uncommon for this to be a real life issue. A trace amount of chili in a recipe will not cause problems but it is not an ingredient that I would choose to add to food prepared for dogs.
• Cinnamon is not toxic in dogs, but if a dog ate a lot of it (eg chewing cinnamon sticks) then there may be some irritation to the mouth, just as there would be if humans chomped cinnamon sticks.
• Citrus Fruit - the flesh is edible, but the rind is potentially toxic. However the rind is also unpalatable, so dogs are very unlikely to eat it. And most people are unlikely to try to feed it to their dogs anyway.
• Cloves are fine to give dogs if they have been used to flavour food, but they do contain a chemical called eugenol which in high doses could cause liver problems. However, cloves are not palatable to dogs, so they are unlikely to munch enough cloves to cause a problem. If your dog raided your spice cupboard and ate a boxful of cloves, then you should contact your local vet, but this is highly unlikely to happen.
• Jackfruit - No harm in moderation, like most foods, but again, feeding the entire fruit, including the rind, in large quantities, would not be advisable, even though it would be unlikely to result in toxicity.
• Lemongrass is nontoxic, but if a dog ate large quantities, it could, conceivably, cause a digestive obstruction. However, the same applies to many objects in the environment, and again, this should surely be common sense.
• Stone Fruit - the flesh is safe to eat, but if dogs crunch up the stones, their centres contain a type of cyanide which is toxic. But it is common sense that you should never feed whole fruit with stones of any kind to dogs, as the stones also form potential foreign bodies, causing gastrointestinal obstruction. That's why this type of poisoning is theoretical rather than a real-life day-to-day issue...
Foods to avoid,
Garlic is the big one to avoid. It’s in the same family as onions, and dogs can suffer damage to their red blood cells caused by the chemicals in both of these. For this reason, it’s better to avoid routinely feeding dog or cat foods with garlic or onion in them, because even small amounts can damage red blood cells. That said, the quantities of garlic or onions that we use to flavor most human dishes are unlikely to cause enough harm to make pets ill, especially if they only have them once in a while. Problems are most often seen when dogs eat large quantities e.g. eating a dish made primarily from onions or chewing a container of garlic powder.