Place the clam juice, water, squid ink and saffron in a small sauce pan. Bring to a gentle boil and then lower the heat to let it cook for another 1 minute. Remove from the heat and set aside to let the saffron threads infuse the liquid
Place the ingredient for sofrito in a food processor and process until smooth.
Cook the rice:
Preheat a large paella pan or if you don't have one like me, I just use cast-iron skillet. Add cooking oil. Add the sofrito and cook for about 5 minutes. Add the smoked paprika, saffron, pinch of salt and cook for another minute.
Add the rice and stir to combine. Add the clam juice mixture, into the pan. Spread the rice evenly and thinly on the surface of the pan. Bring the broth to a boil and then lower the heat to maintain a gentle steady simmer. The rice will gradually absorb the broth and try not to disturb the rice while cooking, this will take about 15 minutes or so and at the same time, the crust (socarrat) will form at the bottom.
Arrange the mussels pieces on top of the rice and let them cook again for another 5 minutes. If the rice is cooked but the mussels are still not cooked through, cover the pan with aluminum foil and lower the heat and let it continue to cook until the mussels are cooked through. The cooked mussels will open up and discard the ones that aren't.
While the paella is cooking, let's sear the scallops. Pat them really dry on both sides with absorbent paper towel.
Sear some scallops while the rice is cooking:
Preheat another non-stick pan with 1 Tbsp of oil. When the pan is hot enough, gently place the scallops about 1 inch apart, season with a bit of salt and let them sear about 2-3 minutes on each sides. Remove from the pan and arrange on top of the cooked paella.
Back to the rice:
At this point, the rice should be cooked through and the rice at the bottom of the pan should have some short of caramelization or stickiness to the pan. Remove from the heat and let stand for 5 minutes before serving. Add some fresh parsley leaves and fresh diced tomatoes for color contrast. Serve with lemon wedges if you wish