levite

OK, basically, you want to start with a few things:

Teach them a couple of cooking theory points, such as: flavors build in complexity and intensity. That's why, when you're making a soup, you don't just toss some meat and vegetables in a pot, pour water over it, and then when it's hot enough you have soup. It won't be soup that way. You go bit by bit, adding ingredients and cooking them down, you use stock instead of water.... Also, teach them about caramelizing sugars, and how to reduce liquids. Once people know why you have to follow certain steps in cooking, it becomes a lot easier to figure out doing it, and what went wrong if something does go wrong. A cooking basics book might not be a bad idea for them.

Next, it is imperative to let them know that food will only be as good as the ingredients used. It is never worth it to get canned foods, except for beans or tomatoes. Always get the best fresh vegetables possible, and if what you want isn't available fresh, get it frozen, not canned. Don't just rely on the meat and seafood departments at your local supermarket. Find a good butcher and a good fishmonger, and cultivate a relationship with them. Know where your meat and fish come from, not just for ecological purposes, but because fresh meat from well-treated animals is tastier and more nutritious; likewise, seafood that does not come from tainted waters, or which is not prone to retaining mercury and other chemicals in its flesh is far better for you and far tastier than seafood of unknown, maybe literally murky, origins. Quality meat and produce are deeply worth the money. Food which is less nutritious and not flavorful will make your life miserable, and will be a sure turn-off from cooking. Plus, fresh vegetables, fruits, fish, and meats, are ultimately cheaper than buying a cartload of prepackaged or ready-made food, which is always grossly overpriced.

I would start the actual lessons with things that are easily salvageable from mistakes, and which impart good lessons in cooking. Soups, stews, and pasta sauces are good bets. Teach them what roux is (flour and oil in equal measure cooked into a paste at the beginning of a soup or sauce, to which liquid is then slowly added, resulting in a thicker liquid). Simple broiled chicken and pan-fried fish are also good starters.

It's also never too early to make sure they know never to over-cook vegetables. Nothing is sadder than an overcooked, limp piece of produce. Asparagus or snap peas can be steamed or blanched very quickly, and come out nice and tasty. Artichokes can be steamed or boiled with great ease. Cauliflower or brussels sprouts should be sprinkled with olive oil and roasted in the oven for 45 minutes to an hour at 375. Baked potatoes are always a good bet, because they can be microwaved, much like yams, which are always a nice treat. And so on....

Casseroles are another good starting point: tasty, filling, cheap to make, and a single casserole can be several meals.

Finally, don't forget dessert: chocolate chip or sugar cookies are pretty easy to make, as are baked stuffed apples. Things like that can really brighten up life for the budding cook.

Finally, make sure that they have decent equipment to cook with. A couple of good knives is a must, likewise, a food processor, an immersion blender, a couple of good cutting boards, and some quality pots and pans-- I recommend including at least one enameled dutch oven, if possible. If cost is an issue, look for these items on eBay, or Craigslist, or as a last resort, in thrift shops. They can be found for reasonable prices, if one looks hard enough.

__________________
Dull sublunary lovers love,
Whose soul is sense, cannot admit
Absence, because it doth remove
That thing which elemented it.

(From "A Valediction: Forbidding Mourning" by John Donne)