Put the saffron threads into a small pan over a medium heat with the sherry and warm them, not letting the liquid come to a boil. Remove the pan from the heat and let cool.
Heat the oil in a wide, heavy based pan over low heat. Add the onions and saute for a few minutes.
Add the sliced garlic and cook for a minute or so more. Stir in the rice, coat the grains in the oil, then add the prawns, baby squid, pork and peas. Mix to combine.
Heat the chicken stock in a small pot over medium heat, or make up the concentrate or cubes with boiling water. Stir in the sherry and saffron mixture and combine well. Add the stock mixture to the rice and bring it to a bubble, then turn the heat down to a low simmer, but leave uncovered.
Cook without stirring for 15 to 20 minutes, and by that time the rice should have absorbed the liquid and be tender. Gently stir with a fork to separate the grains, and check the seasoning, adding salt, if needed.
Serve the paella edged with lemon wedges, and sprinkled with cilantro.