The text looks like it was taken from a recipe. It has the chatty tone of a cookbook writer. Randy and Helena have adequately addressed the meaning of the first sentence. As Helena explained, the second part of the second sentence urges the reader to "try and make sure that the greens are cooked until tender (soft) and slightly crisp (crunchy). The first part of the second sentence appears to be an attempt at humor and suggests that the reader should not follow the suggestion if it means "standing over an angered chef who is holding a cleaver (a butcher's knife)". The idea is that some chefs can become prickly when someone is monitoring their work ("standing over them") and tries telling them how to cook. The best thing is to avoid meddling with the cook's work and let him (or her) cook the plantains in whatever manner they wish to. After all, if the riled chef is holding a cleaver, one might find the chef cutting something other than the food being prepared.

Basically: The rules for cooking plaintains using this method (whatever it is, there's no context to tell us what method) is the same for cooking the other greens. [The first part of this second sentence makes little to no sense without more context] Make sure that these (the other greens) are cooked until tender (soft) and slightly crisp (crunchy).

It's a little difficult, absent context. The passage relates to a certain method of cooking, and plantain is considered similar to other wild greens. The second sentence is too unclear.