Sage and mint do well here in Pittsburgh under conditions of benign neglect. (Mint will take over the world if you let it) Basil does too, but it grows as an annual that dies at the first snowfall. We also had good luck with rosemary, thyme, and oregano, though I’m not sure the rosemary or oregano survived the winter.
I’ve yet to encounter a garden veggie for which watering twice a week isn’t enough, even in a semi-arid environment like Montana. I’m sure Toronto gets more rain than we do. Starting from seeds, though, you might get some cherry tomatoes, but you’ll never get any full-sized ones.
Another possibility, for vegetables that are really easy to grow, is to look into which of your indigenous weeds are edible. I’m sure you get dandelions there, which are one of my absolute favorite foods, and you can probably find purslane as well. But if you’re borrowing a corner of your mom’s garden, she might or might not appreciate this.
Yes, when they say mint is “invasive”, they aren’t kidding!, I have a mint plant in my Aerogarden that’s almost as tall as my basil, and not only is it not satisfied with trying to outgrow my basil (the hood is on it’s tallest setting and the basil still burns at least one leaf a day on the flourescent lights, I have to cut it back every other day), it’s sent runners around the entire length of the water resivoir, and sent above-ground runners out trying to reach the dirt pots of chives, carrots, and borage I have clustered around both Aerogardens, I have clipped those runners back, but it’s clear that this plant truly wants to take over the world…
and even worse, it’s now decided that the flourescent lights in the standard two-bulb AG6 where it’s planted are not good enough for it, NOOOO, now it’s leaning over towards the brighter lights of my three bulb AG6 Elite+, it wants that light too, it’s actually competing with the rightmost cherry tomato plant in the AG6E+ for light, but on the upside, mint is one of the reccomended companion plants for tomatoes, it makes them grow stronger and healthier, the same with basil…
greedy plant, that mint, it might be time to prune it back, although I’m kinda’ curious as to how out of control it would get if left to grow unchecked…
Hmm, wonder if I should call it “Brain” (from Pinky and the Brain) or “Audrey II”…
Yes, be very cautious planting mint, it’s best to keep it in containers
I live in the Bay Area, and I’ve given up on jalapeños. They grow just fine, but they don’t have any heat. I’m not sure if it is the heat or my soil, but I’ve decided it makes more sense to get them at the farmers’ market. When I lived in Louisiana, though, I grew outstanding ones. Bell peppers, though, do just fine.
Lissla, I can also provide mint clippings if you’re willing to wait until June or thereabouts - trade you for some rhubarb?
We have a mint patch that was planted by previous owners, and which has proved to be completely unkillable. (I’d recommend planting in a container to avoid having your vegetable patch forcibly repurposed into a mint patch)
Sure you can. You just start the seedlings indoors a couple of months ahead… a sunny windowsill is more than adequate for getting started, and once the risk of frost has passed in May, you stick 'em in the ground. Admittedly not as easy as just planting seeds right into the ground, but not exactly on the same level of difficulty as brain surgery.
Either that, or I’ve been growing some surprisingly large cherry tomatoes. 
Toronto isn’t the arctic tundra, folks - we’re a USDA Zone 5b or 6a depending on which map you’re looking at, which makes us warmer than parts of Montana, as well as Wisconsin and Minnesota… and on par with Iowa, Pensylvannia and Missouri.
I think that the various pepper varieties can cross-polinate, and since most of the heat comes from the seeds, you get a mix of the properties of both parents. So jalapeños grown in amongst other jalapeños will be normal jalapeño hotness, but if grown amongst bells, they’ll be milder than they should be, and if grown amongst genuinely hot peppers, they’ll be hotter than they should be.
I love breaded & fried zucchini–dust it with cornmeal or the like. It’s edible raw & straight.
Easy to grow, hard to kill? I’d think cabbage & some of the onion/leek family, but I’m from much further south than you.
If the winter hadn’t pruned ours, I suspect it would have eaten Pittsburgh by now and be working on devouring Cleveland.
That said, if you’re able to water things, I don’t think any annual vegetables are really hard to grow. You could grow some other squash/marrows, & melons (which grow like squash) pretty easily, but the melons will want lots of water.
I find that the easiest thing in my garden is spinach. Here in the bay area, I can grow it over the winter, as well as plant some more in the spring. I thin it once, and then the stuff grows itself with no tending except for watering. It provides little baby leaves for salad as well as big honking leaves for cooking. I just pick the leaves and let the plants keep producing. Bugs don’t seem much interested in it - stupid picky bugs!
However, once the weather gets hot, it does bolt.
I’ve done a little reading about peppers, as I like to grow them. It’s not the seeds that are hot per se, but that light colored fleshy membrane the seeds are attached to that contains the most capsaicin. It gets on the seeds though, if you’re not really careful.
Pepper cross pollination is only troublesome to the second generation plants grown from the cross pollinated seed. I get all sorts of whacky results that way. I’ve got some chiltepins that have a wonderful sweet juicy taste but will knock you flat on your back with heat, within about 1.5 seconds. I’m not sure what they crossed with.
But the fruit of your first generation peppers should be fine.
What makes hot peppers hotter or milder is growing conditions, and it’s a bit of a toss-up. It’s about “stress.” But stress can be too hot, too cold, too dry, too wet, too much fertilizer, too little fertilizer, etc. It takes some experimentation to see what’s going to make your hot peppers pump out extra hotness.
The ones in the supermarket vary quite a bit in hotness, too. I’ve gotten some jalapenos my parents could probably have eaten, lately 
Okay, i withdraw what I said about other people not loving zuchinni. I really do love it, though. Not many people are passionately fond of the stuff.
What’s interesting about zuchs is how big they get. Normally you pick them when they’re more or less pickle size, but if you let them go, you end up with a zuch the size of a loaf of bread. I didn’t know that until I grew them.
BTW, if you have an aquarium with a plecostomus in it, plecos love to munch on a slice of zucchini.
Basil is a good suggestion, if you like it. Fairly hardy and can stand a little bit of drought. Plus easy to grow from seed or you can buy plants.
Go with cherry tomatoes if you do tomatoes; it’s a lot more fun having small but ripe ones every day than waiting all summer for a half-dozen full-sized ones. You’ll want to either start the seeds indoors (pretty soon) or buy plants.
If you do grow zucchini, remember that bigger ones get tougher and less tasty; it’s not all about size.
Peas and beans
My experience with potatos has bene that you dig a hole, toss a potato in it, forget about it for a season and then come back in the fall when the potato plant has started to die off and use your gardening fork to pull up a mess of cat-sized potatos.
And this was in crappy, lime-filled soil next to the house foundation in the Chicago area.