A basic spaghetti bolognese is relatively easy and very tasty. Also learn how to make a curry, it's very easy and allows for almost infinite variation in veggies, meat spice combinations, etc... I would also advise you to learn how to make a basic soup, because that also allows for infinite variation once you know the basics.

Both curries and soups are also quick to make. Both can be done in 30 minutes (at first it will take longer of course, but with practice it will go faster).