Still not quite in the mood, hence the somewhat oddish subjects of not only this post, but the two posts immediately preceding. Think of them as lazy lagniappes.
The standard recipe for lime or lemon pickles starts off with three TBS salt and three TBS cayenne for either two large lemons or six, seven limes.
[The proportions are the same for a green mango pickle, using two very green mangoes.]
The lime or lemon is cut into quarters or eighths, salted, and put in a clean wide container to dry out for a day or two or three - in direct sunlight if possible. It is wise to cover it with cheesecloth to keep out shrotzim during this time.
And from there on it varies. The chunks of lime or lemon have by now reduced somewhat in size and exuded some liquid - all is scraped into a clean jar, and the cayenne is mixed in. One or two Tsp toasted brown mustard seeds are usually added, along with some fenugreek for flavour and a saucy mouth-feel, plus turmeric (teaspoonful) and asafoetida (generous pinch) for preservative qualities.
For the next week or so the pickle jar is put in the warm sun for a few hours and shaken once or twice per day to redistribute the juices and spices. Once it has reached the right stage of pickledness some heated mustard oil is poured over - enough to cover each piece of citrus with a thin film.
Hyderabadi lime pickle tones down the chili content, but adds garlic (which mellows with age) and accents the garlic with anise-type flavours (usually fennel seed).
Kalonji (wild black onion seed) is almost always added to muslim pickles (such as Hyderabadi lime pickle) - it is a taste preference that came with the Muslims from Afghanistan when they established their last empire in India (the Mughal empire).
Commercial pickles often use far too much oil. The oil functions as a sealant to the pickle, preventing exposure of surfaces to air. But the salt and acid (the juice of the limes or lemons) are what preserves this type of pickle - oil is far less necessary than with other pickles like cauliflower pickle (Poolgobi ka achar) or green mango pickle (Amb ka achar).
A well made lemon or lime pickle keeps nearly forever (because of the acid and salt), as also do other Indian pickles where the primary ingredient has been partially dried and heavily salted.
Final note: Kagzi nimboo makes excellent pickle.