I found interesting thing: during eating large amount of eggs my strength rise occasionally. Is there any other regular food I can eat in large amounts to rise statistics?

Apples raw, some recipes for clod, shark and some more. Spices are important to keep.

I found a great recipe for a hotpot stew that gives +200hp healing, but apparently potatoes are rarer than gold on this island.

The strategy should be as follows:

1. use the trainers to get up STR, DEX (you get a shitload of WIS from books, no need to pay attention) to 100, which is their cap increase
2. collect rare ingredients, which give permanent boost, for later until you know the recipes
3. use food like eggs and apples raw for STR past 100
4. use cooked meals to boost DEX, max-HP and max-Mana permanent
5. use alchemy with the ingredients you collected earlier to boost STR, DEX to 200