Very good question! If the word is THINK (instead of CONSIDER), then it should be Many french chefs think Kampot pepper is the best in the world. But, CONSIDER is different from THINK. CONSIDER *includes* IS. For example: I think you are the best! = I consider you the best! He thinks farting is rude. = He considers farting rude. She thinks cats are cute. = She considers cats cute. BUT: You can only use this to say what somebody thinks *about* something. For example, you can NOT SAY: * He considers the cat hungry. That would be very strange... So, here you SHOULD SAY: He thinks the cat is hungry.

Because you don't need it. The long sentence is: Many chef consider Kanpot pepper (to be) the best in the world. consider something to be good = consider something good consider something to be nice = consider something nice

Many french chefs consider Kampot pepper the best in the world. and Many french chefs chonsider THAT Kampot pepper IS the best in the world. mean exactly the same