I like your reasoning, lulu...always good to encourage kids (adults, too) to try new foods before making faces and

sounds about them.
Here's one plantain recipe I found for you and your son, although it calls for more than 'just one" and I'm posting a website with a bunch of recipes, depending on the type of plantain you bought and the type of things your son might like you should find something to entice him:
http://www.gourmetsleuth.com/plantain.htm
Tostones de Plátano
(fried plantains)
Serves: six adults
Preparation time: About thirty minutes. Ingredients:
3 or 4 green plantains, peeled and cut at a slant, so that a medium-sized plantain yields around six pieces
seasoning to taste (garlic salt, ground pepper, ground oregano)
Procedure:
Fry in a deep pan over medium to medium-high heat until the pieces begin to turn crisp. It's best to fry a few pieces at a time.
Remove the pieces. Set over a firm surface and press down on each piece with a hard instrument such as a roller until it becomes flattened thin and elongated. (Unless, of course, you avail yourself of a Tostonera - a gadget that will press the plantain piece into the shape of a Toston)
Return to the frying pan and continue to fry until they look quite crisp. Remove excess frying oil by setting over paper towels.
Use as a side dish to substitute for French fries. Warning: your diners may not want to go back to French fries in the future!Use as a side dish to substitute for French fries. Warning: your diners may not want to go back to French fries in the future!
You can freeze the plantain pieces before the second frying. They will last for months in the freezer! Careful, though: "for months" doesn't mean "forever"