Place the saffron threads in a small bowl and soak them in 2 tablespoons of warm water. Set aside.
Heat the olive oil in a wide skillet or paella pan over medium heat. Add the diced onion and garlic and cook for about 3 minutes, until softened and fragrant.
Add the diced bell peppers and sliced chorizo. Cook for 4-5 minutes, stirring occasionally, until the peppers soften and the chorizo releases its oils.
Stir in the rice and cook for 1-2 minutes, allowing it to lightly toast and absorb the flavors in the pan.
Add the diced tomatoes, chicken broth, and saffron water. Season with salt and pepper and mix gently to distribute the rice evenly.
Bring to a gentle boil, then reduce the heat to low. Simmer uncovered for about 15 minutes, without stirring, until the rice is tender and most of the liquid is absorbed.
Nestle the shrimp into the rice and cook for 3-5 minutes, until the shrimp turn pink and are cooked through. Remove from heat, cover loosely, and let rest for 5 minutes before serving.
Garnish with fresh parsley and serve warm.