Look at what's in front of you
Many (most?) of us look to recipes to tell us what to do in the kitchen. What ingredients to use and how much of them we need, what to do with them in which order, and how long it will take to cook. And a few of you have told me you do indeed worry about not knowing what goes with what or when it's done without a recipe to tell you.
So how can you tell all these things intuitively? Is it even possible? (No, I don't mean memorising the recipe). Here's the secret:
Look at the food in front of you.
What goes with what is entirely determined by cultural and personal preferences. In Britain you add swede and carrot to a stew, in Iran you add pomegranate and almonds - and that's just one example. Anything goes, as long as you like it. There are 'tried and tested' flavour combinations, of course, but these too are specific to your taste (and those you cook for).
Don't expect a recipe to tell you what to like - learn to trust your taste. Pay attention to what you like and what you don't, and keep notes (mental or in a notebook). My head is most definitely a huge 'library' of taste memories! That new recipe you made last month, or something you ate on holiday, or what you love about your favourite dish - what combinations appeal to you? And which not so much? From there you can extrapolate and improvise (yes you can!).
For example, if you know you like garlic with spinach, chances are you will like garlic with any kind of greens. If you loved a dish of roasted fennel and tomatoes, you can assume you will like the addition of fennel in your tomato sauce, be it fresh (both the bulb and the fronds!) or as a spice (the seeds).
Another path to figure out tasty matches it to think of the main ingredient you have and think of what could complement or contrast that taste (ideally both - think about layering flavours here.)
Say, you have a squash, and you want to make soup. Squash is sweet and creamy, so you can enhance that with other sweet veggies (carrots and potatoes perhaps), and with the sweet creaminess of coconut milk. To contrast the sweetness you could add, say, garlic, ginger, tomato, and/or nutmeg. And next time you have a squash you could roast it with the same ingredients (i.e. garlic, ginger and/or tomato to contrast, while roasting in itself will intensify the sweetness).
How much do you need? If you think about it, it becomes obvious:
Base ingredients (say, how much tomato for a pasta sauce) are determined by the portions you are cooking (e.g. enough for 2 or 6 or for leftovers).
'Extra' ingredients depend on what you like (see above), what you have to hand and how much food you are making. I always think in terms of 'what else can I add'? That way I get to use up what I have, and I dial up the variety of foods we eat in every meal too (always a good thing).
To gauge how much liquid you need, look at the consistency. Are you making a stew or a soup, or do you just need a splash of water to stop your stir fry sticking? Remember that juicy' veggies like tomatoes or courgettes will contribute liquid to the pot as they cook. Keeping the lid on will also conserve liquid, while more will evaporate with an open pot.
The best way to find out how much of a flavouring (spices, etc.) you need is to keep tasting: add a bit and then some more until it tastes 'right'. You'll get the hang of how much you need/like pretty soon. (My tip: a pinch of anything is never enough!)
Sometimes the relative quantities (the ratios between ingredients) are important, for example in baking or certain sauces.
Work out the proportions - this is much easier to remember and to 'translate' into different cooking situations. (e.g. a salad dressing usually works in a 3:1 ratio - 3 parts oil to 1 part acid - this could be spoonfuls, cupfuls, finger-highs, etc).
Yes, I know this can be tricky with baking and I would be more cautious here (I admit I'm not a big baker). Still, most US American recipes use cup measures (i.e. proportions) and these looser measurements do work as well as gram by gram weights.
Again, if you pay attention you will soon become familiar with the 'correct' consistency you need to achieve (the way a spoon ripples a sauce or the dough starts sticking just so.)
Of course, there are sophisticated techniques, and if you are so inclined, it could be fun trying something complicated on a weekend perhaps. But for simple everyday cooking you only need the very basics of cooking in a pot/pan or in the oven. And if you look for the patterns (more on this concept here) you'll see that most methods move on a continuum you can easily move up or down. A few extra tips:
Dense (i.e. hard and heavy) or chunky ingredients need longer cooking. Put them in first. Light and delicate ones cook faster - put them in later, or even right at the end. (Btw, the same applies to tray bakes in the oven.)
Dense ingredients can be made lighter by finely chopping or slicing them (I love using a potato peeler to make carrot ribbons that cook as fast as leafy greens.)
Think flavour, think layers: I almost always start with a flavour base of aromatics (onion, garlic, celery, carrot and/or spices), be it a stir fry or a soup.
You don't need a recipe, or a timer. Pay attention to the food in front of you and you'll know when it's done. (*)
Touch: Cooked food changes texture - usually it becomes softer (how soft or crunchy you like it is up to you). As batters and sauces thicken when the time is right, the way your spoon glides and ripples through will change too.
Look: Food changes colour as it cooks: Watch how greens turn bright green at first and grey green after a while, how high heat causes edges to caramelise in darker shades, and how a dressing or sauce turns glossy when it binds.
Smell: The smell changes too. Heat will intensify and develop aromas at first, then make them sweeter, then turn sharp and bitter.
Taste: There is no right or wrong. Trust your taste to tell you when it's right for you.
Now go and give it a try: watch your food while it cooks. What can you see, taste and smell?
* The only exceptions I can think of, where a timer and/or thermometer are kind of necessary are those situations when you can't look inside: boiling eggs and roasting a very large piece of meat, like a whole turkey, come to mind.