Add 2 tablespoons olive oil to the paella pan and reduce the heat to moderately high. Add the squid and season with salt salt. Cook, stirring, until starting to brown, about 2 minutes. Add the remaining 2 teaspoons of olive oil, and reduce the heat to moderate. Add the minced garlic. Cook, stirring, until fragrant, about 15 seconds. Add the onion and cook, stirring, until translucent and soft, about 2 minutes. Add the tomatoes and cook, stirring occasionally, until the tomatoes turn a dark brick red and start to stick to the bottom of the pan, about 5 minutes.