Peel carrots and onions. Cut onions in quarters, leaving root ends in tact, so that they hold the quarters together. Cut carrots into 2 - 3" pieces, and if the carrots are really fat, cut them lengthwise into halvves or quarters. (You can adjust the quanitities of everything -- it's just that the program here wants specifics.).
Put them onto a cookie sheet or jelly roll pan and drizzle with olive oil and salt and mix them with your hands so that they are lightly coated. The pan does really matter here -- if you use something with sides, they steam rather than roast.
Roast for 15 minutes, turn and roast for 15 - 30 minutes more. At this point, they should be cooked, but they can go longer if they're not done. they should be crisp/tender (if they go longer, they get soft, which I'm starting to like, too) and have browned spots on them.