This is the method I've used to make some painfully lovely flavoured vodka. If you're not much on alcohol, it can also be used to flavour oils or perhaps syrups, for a sweet version (I haven't experimented with syrups though.) You just need something that will provide preservative action; anything with a sufficiently high alcohol, oil, or sugar content should work.
These aren't really recipes as such, you could use any ingredients you like and improvise. All ingredients are quanticised to personal preference.
I don't have a schedule for how long to 'age' these for. I've had mine for over a year, but they were pleasant and drinkable at a month or so.
Vodka or similar unflavoured grain alcohol (does not need to be high-end, but preferably not something your disreputable mate distilled out of an old engine block)
...if not using vodka, olive (savoury) or sunflower (neutral) oil...
...or previously-prepared heavy sugar syrup
Perilla leaf (aka. shiso, and optional 'cos you probably won't have any, but it's worth seeking out)
I'm not calling it proper limoncello because it probably isn't, but that's the non-homemade drink it most closely resembles.
Make sure your base- vodka, oil, or syrup- is in a clean and airtight container.
Quarter the lemons, or until they fit in the bottle. Try not to lose any of the juice (so slice them over the bottle, or in a funnel or something). Chop up the leaves, then add all ingredients. Shake. Leave for ages, or until you're bored.
If you're making savoury lemon oil, best to leave out the sugar. I suggest adding: garlic, thyme, rosemary, and salt.
I don't ever remove the ingredients from the finished product, as you can just pour off the liquid.
Rose petals- make sure they are properly scented
Combine. Shake. Leave. That's it. The rose petals will lose their colouration and the eventual result will be a pleasant golden shade (at least if you use light flowers; I have not tried this with dog roses, yet) with rose petals floating ephemerally about. Petals can be ganked in large amounts from public displays in summer (you don't need sufficient amounts to denude a whole bush) then frozen until you need them.
If they're out of season and you're desperate, you can use rose essence but it won't really be worth it. Don't on any account use pretty garden roses that have been bred to look perfect but have zero fragrance.
I have two versions of this, a liqueur type (sweet) and a savoury one which is more like alcoholic soup. Both are painfully hot; the latter is particularly good for shifting a blocked nose, which is one of its traditional uses in Russian cuisine. In Russian it is 'pertsovka' which I will call it from now on 'cos it's a syllable shorter.
Use your preferred chillis. I used red large cayennes, because they were what was available; I think a green jalapeno version would be marvellous, likewise a Scotch Bonnet and tropical fruit combination, or Thai birdseye and lemongrass, although less Russian. Not that cayennes are especially European... anyway; if you are not fond of mouth-blistering, use a milder chilli- even a plain traffic-light pepper would yield excellent results. If you are sceptical about the combination of Scovilles and sweetness, then I have nothing more to say to you.
Slice the peppers in half or until they're small enough to fit. Don't take the seeds out (no, they aren't 'poisonous', *and* you can go swimming less than an hour after eating too). Combine all the other ingredients. Leave somewhere.
I use this method- with oil- for making the marinade for olives and feta (listed below). I use so much of it, it's more practical to make up a jar of the concentrated oil+spices and keep it around.