We want to know: What's your favorite thing to accomplish in 5 minutes?

Another 5-minute-ish start-to-finish task is to make tomorrow morning's steel cut and rolled oats for breakfast. If you have warm water in your tea kettle (which I almost always do while making supper), bring 4 cups to a boil, pour into a heavy saucepan with a pinch of salt + 3/4 cup each of steel cut and rolled oats. Bring back up to the boil. Stir in a couple dashes of cinnamon and a good dash of ground allspice (or add pie spice or mixed spice to taste, or no spice) and a small handful of raisins or other dried fruit. Turn down the heat so it doesn't boil over. Boil for about a minute. Cover tightly, let sit overnight. Give it a good stir in the morning while heating gently to serve.

If you have to start with cold water, heat half in the covered saucepan and the other half in a tea kettle; combine when the kettle comes to a boil. From cold water, depending on your BTU level, how cold the water is, etc., this will take 7 - 8 minutes, with less than 1 minute of active time. Starting with warm water? Less than 5, easily. I've been doing this for years. You can use milk instead of water for a much richer breakfast. Don't boil it; scald it and simmer with the oats for a full minute. ;o)

Just timed this w during my lunch break: I can sweep my (small) kitchen's floor in just under 2 minutes and give a weekend's worth of sticky spots "a lick and a promise" with a sponge in about 2 1/2 - well under 5 minutes, but making a world of difference.
Knowing how little time projects like this take makes it more likely they'll be done sooner . . . . ;o)

Another high impact 5-minute project is to make pickled red onion or shallots. I use this recipe https://food52.com/recipes/29712-low-maintenance-fish-tacos, but add flavors such as

*cumin + coriander crushed with black peppercorns, put in the bottom of the jar with a handful of cilantro leaves* or

*allspice, coriander, black peppercorns crushed, with a bay leaf added*

or whatever other combination strikes my fancy.

Put the spices in the very bottom and heat the vinegar solution in the microwave while slicing the onions. ;o)

Another high impact 5-minute project is to make pickled red onion or shallots. I use this recipe https://food52.com/recipes/29712-low-maintenance-fish-tacos, but add flavors such as

*cumin + coriander crushed with black peppercorns, put in the bottom of the jar with a handful of cilantro leaves* or

*allspice, coriander, black peppercorns crushed, with a bay leaf added*

or whatever other combination strikes my fancy.

Put the spices in the very bottom and heat the vinegar solution in the microwave while slicing the onions. ;o)

Depends on the day. Cleaning the coffee pot for next a.m., unloading the dishwasher, cleaning/trimming vegetables for dinner, etc.

But sometimes when I truly only have 5 free minutes during a busy day, I find it's better to just...not.

A minute to play with the dog, text my kids to check in, or just flip thru the paper is often far more valuable to me than trying to 'accomplish' one more thing.

To answer the question you posed - although, again, I can't say necessarily that it's my favorite -- making salad dressing or tahini sauce. Of all the tiny tasks that come to mind, this one strikes me as having a particularly high impact.
I can easily whisk up not one, but two different simple dressings or sauces. (Since I have the bowl, whisk and most of the primary ingredients out, it's a real time saver to do two!) And yes, I use a bowl and whisk. It may take, oh maybe a minute or two extra, to whisk the fat into it in a stream, instead of just shaking all the ingredients together in a jar, but the dressing is less likely to separate that way.
I keep a running note with links of new dressings and similar condiments to try. ;o)

knit 1 row.

go out into the backyard, dig a hole, bury compostables. use hose to wash out compost pot over garden to water peruvian lilies. put shovel back on top of woodpile under eaves. back inside. even had time to look up at sky, the trees and talk to the squirrels.

Cookie icing. It's almost embarrassing how easy & quick it is to make. It can be thick, thin, flavored, glossy, matte.
I just mix powdered (confectioners') sugar & water (or a flavorful liquid).
I made a double batch of sugar cookies but made lots of small batches of different flavor/density icing. Turned a single cookie recipe into a cornucopia of flavors! Yum!

Oh, goodness, there are dozens. The favorite would be the one that needs to be done now. I regularly jot down meal or other project-specific tasks on a medium index card, which I keep handy in the kitchen. (All projects are broken into smaller tasks, which are handled as time permits.)

Last year I pulled together a quick list, off the top of my head, of examples to share with some of the Food52 users I mentor. Here's a link: https://tinyurl.com/SmallMakeAhead By no means is it comprehensive, and of course, each person's list will be different.
(I keep similar lists in the office of tasks easily knocked off during pockets of "down time" when conference calls are delayed, when I have a bit of extra time between meetings, etc.)

One task not mentioned in the list is this: I clear out the drain rack next to the sink every morning while the kettle is on for tea. With such a small kitchen, it's nice to have clear counters when there's no project underway. ;o)

My random (and partial) list of 5-minute tasks:
Start a load of laundry
Apply a coat of nail polish
Fill the bird feeder
Swiffer/dust the floors in a couple of rooms
Clean up my laptop's desktop
Make the bed
Water the potted plants outside
Daydream : )
Check out the Food52 Hotline!

Loading and/or unloading the dishwasher and cleaning sink.

Interesting question. I set the timer on the oven and then start moving! Fold kitchen towels, put away clean dishes and feed the backyard birds and change the birdbath water. Each time I challenge myself and make a game out of it. How much can I do in 5 minutes that I haven’t done before? BB😎

I'm OCD when it comes to preparing for the next day/task/five minutes, so I'm always looking to have things portioned, laid out, or set up to grab and go. Particularly during the week, 5 minutes is enough time to...
-set up cold brew coffee,
-throw together a bag (or four) of snack-y things (all hail the pantry stocked with jars of nuts, seeds, dried fruit, roasted chickpeas, edamame, toasted nori, etc...)
-wipe down the counters in between food prep
-Mise en place the non-food items for the morning rush, like keys, tote bags to be packed and taken, electronics, and the like
-replenish workhorse DIY ingredients - chop the top off of a head of elephant garlic, drizzle with olive oil, and roast whole while the rest of dinner is cooking. I store is whole and use the cloves; Make a pesto with leftover herbs, lemon, oil, salt and pepper; Toast nuts and/seeds for the week or just for dinner. Throw in a small pan for a few minutes or onto parchment and into the oven with the rest of the night's fare.

OR

-Take five minutes of rest, text a good friend an overdue "Hi-how-are-ya?", and take a well-earned sip of coffee (previously cold-brewed, of course).