By cooking bananas, you are refering to "plaintains". They should have begun showing signs of ripening in a two week period (assuming they're at room temperature). In any case, plaintains can used used at virtually any stage in the ripening process. Actually, some stores sell the same fruit in separate bins depending on the degree of ripeness. Different recipes call for using the plantain at different degrees of ripeness (green, yellow, or even black). I generally buy them very green and make them into plantain chips (very easy and delicious). On the other hand, if you wait untill they get really yellow with black patches (or even black), they can be used in as a sweet. I've used the ripest ones to make delicious plantain shakes believe it or not.

rjinga, that's a good question. In very general terms there are three types of banana plants. The first type would be ornamental, the flower and fruit they produce cannot be eaten.

The next type is the edible banana, or "desert banana". This is the one we are all used to. We let it ripen, then yellow and eat it.

The last veriety is the plantain. That's a banana that must be cooked prior to eating. It's like a potato. You can leave it on your counter all you want, but it's not till you cook it, that it will be edible.

That sounds like what you have.

If you have a plantain, the best way to cook it is to fry it, like like potato. My wife is from Puerto Rico and when she cooks them, she'll cut them in 1/4 medallions, crush them a bit and then fry them. Do this when they are green.

I believe this dish is called "platanos". Try a google search for more info. It's well worth cooking. Try it, you'll like it.

Good luck!