This Seeking Tech tutorial will show you how to get the Just What the Doctor Ordered trophy and achievement in the Master Collection version of Metal Gear Solid 3: Snake Eater.
To unlock this, you need to “collect every type of medicinal plant.”
You can find all of the required items at Dremuchij East, which you will get to near the start of the Snake Eater mission. Use the following video to find the exact locations of the medicinal plants.