Rinse out the squid with cold water and pat dry.
Add oil to saute pan and, when at medium heat, add onions. Allow to sweat for 3-5 mins until soft.
Break up morcilla/sausage with your fingers and add to pan. Continue to break up with a spoon while it cooks.
When onions and morcilla are well combined, add garlic and paprika/pimenton, and mix well.
Increase heat to medium high and add lemon juice.
When ready, mixture should be well-combined and pretty coherent rather than loose or solid.
Allow to cool enough so you can handle it.
Fire-up your grill/barbecue to medium-high.
Salt interior of squid lightly and stuff with mixture and “sew” top closed with a toothpick.
Do not overfill. Squid shrinks when cooked and too much filling will cause it to leak and make a mess of your grill.
Meanwhile, preheat a griddle pan over a high heat. Grill the stuffed squid on both sides until chargrilled.
Remove from grill and allow to cool a little.