Set the 16 juiced lemon halves on a cutting board and pack each one with salt. (You'll have some salt left over. Save it; you'll need it in step 2.) Place the lemons in an 8-cup/½-gallon jar, cut side pressed against the glass. As you layer the lemons, sprinkle in saffron, fennel seeds, black peppercorns and a bay leaf or two.
Pour the lemon juice over the salt-packed lemons (they should be completely submerged in juice, or they will get moldy) and add any remaining salt. Cover securely, then give the jar a light shake.
Let the lemons sit at room temperature for at least 2 weeks and up to 3 weeks before using. Once the jar is open, store in the refrigerator for up to 6 months. To use the preserved lemon, rinse it under cool water, scoop out and discard the pulp, and use the preserved rind.