Heat a large paella pan (or large sauté pan) over medium heat. Add the olive oil. When oil is hot, add the onion and sauté for 5 minutes, until onion is softened and turning golden. Add the garlic and sauté for 30 seconds.
Add the tomato paste and continue to cook until it is completely mixed in and the onions are rust coloured, 2- 3 minutes.
Add the salt, paprika, chili flakes, turmeric and saffron, stir to incorporate.
Add the rice and stir fry until the rice is completely coated with the oil and spices.
Stir in the stock. Bring to a simmer.
Reduce heat to low and simmer for 10 minutes.
Add in the sliced chorizo and cook for about 5 more minutes.
Arrange the shrimp on top. You may need to press the shrimp into the rice with a spoon so that they are almost covered with the remain liquid. Cook for 5-10 min until liquid has been absorbed or evaporated.
Sprinkle with parsley on top and serve hot.