I think it depends on how you cook ur food. I noticed that when eating boiled meat together with the liquid I got the best digestion. I pair that with raw milk of goat or sheep and raw soft cheese. 3 months ago I started the carnivore diet, and after some experimentation I can say that this seems to be the best way to cure food sensitivities as its the ultimate elimination diet. I used to fry ground beef or ground lamb with tallow, goose fat or lard, together with raw dairy, but it was still too hard to digest on low HCI. Now, with the soft meat broth including the meat (lamb and beef), paired with raw dairy things have improved vastly and my HCI is increasing naturally. Eating everything in the broth could mean that you loose little of the nutrients, surely the meat is degraded to some point, but boiled could be the best way to eat cooked foods after raw. Also because it´s soft and your HCI, hence your body, won´t need that much energy to break down the hard food particles to get the nutrients out.
In fact, I came to eating boiled meat by the story of the greek historian Herodotus, which lived around 2500 years ago.
https://en.wikisource.org/wiki/The_History_of_Herodotus_(Macaulay)/Book_III18. Now the table of the Sun is said to be as follows:—there is a meadow in the suburb of their city full of flesh-meat boiled of all four-footed creatures; and in this, it is said, those of the citizens who are in authority at the time place the flesh by night, managing the matter carefully, and by day any man who wishes comes there and feasts himself; and the natives (it is reported) say that the earth of herself produces these things continually.
23. Then when the Ichthyophagoi asked the king in return about the length of days and the manner of life of his people, he answered that the greater number of them reached the age of a hundred and twenty years, and some surpassed even this; and their food was boiled flesh and their drink was milk. And the funny thing is that even back than the King of Ethiopia knew that Grains are crap
http://www.sacred-texts.com/cla/hh/hh3020.htm22. Then when he came to the wine, and had learned about the manner of its making, being exceedingly delighted with the taste of the drink he asked besides what food the king ate, and what was the longest time that a Persian man lived. They told him that he ate bread, explaining to him first the manner of growing the wheat, and they said that eighty years was the longest term of life appointed for a Persian man. In answer to this the Ethiopian said that he did not wonder that they lived but a few years, when they fed upon dung; for indeed they would not be able to live even so many years as this, if they did not renew their vigour with the drink, indicating to the Ichthyophagoi the wine; for in regard to this, he said, his people were much behind the Persians. Either way, this "Table of Sun Diet" seems to be working well for me, so to say that cooked meat is bad is far from the truth, even the people from the world carnivore tribe fb forum eat mainly grilled or highly heated meat, and they heal the craziest health conditions. But they all have something in common. They cut out all plant foods. So the key to good health seems to be low carb and less, or no plant foods at all. If you would now be eating a raw carnivore diet, that might be the fastest way to heal. Just my two cents..
And regarding the last toxic cooked food I could somewhat agree with chestnuts, but the problem is they are very high in carbs. Initially they had helped a lot as they can cleanse the intestines pretty well, but at a later stage they were a no-go. I think tigernuts would be a better choice. In my situation the least irritating foods in the end (before I started carnivore) were sweet potatoes, winter and summer squash, pumpkin and garlic. Asparagus would be ok too. Maybe even artichokes unless u got low HCI, since they have a lot of cellulose and are hard, even when cooked. I also think that rice would be somewhat ok if soft, i think rinsing helps with arsenic levels. But the absolute worst thing that I could think of is sourdough bread. I think Aajonus did a big fuck up recommending gluten bread in his "We want to live", regardless if its made with wild yeast and therefore is lower in phytates. It absolutely wrecked my already sensitive gut.