Step 1
Bring stock to a simmer in a stockpot over medium-low heat. Stir crushed saffron into the simmering stock.
Step 2
Heat olive oil in a paella pan over medium heat. Fry chicken thighs in hot oil until lightly browned 3 to 5 minutes per side. Add onion and garlic; cook and stir until the onion is translucent 5 to 7 minutes more. Arrange the chorizo into the pan around the chicken thighs and cook until warmed 3 to 5 minutes per side.
Step 3
Pour rice into the paella pan and stir to coat with oil; season with sweet paprika. Stir grated tomato into the rice and cook until the tomato is warmed 2 to 3 minutes.
Step 4
Pour chicken stock into the paella pan and bring to a boil while scraping any browned bits of food off the bottom of the pan with a flat-edged wooden spoon. Smooth surface of rice with the wooden spoon in an even layer so it cooks evenly.
Step 5
Reduce heat to medium-low and continue to cook without stirring until the rice has softened but has yet to completely absorb the stock 15 to 30 minutes.
Step 6
Place clams and mussels hinged-side down into the rice; continue simmering until the mussels and clams open 5 to 7 minutes.
Step 7
Nestle prawns into the rice; add bell pepper and peas. Continue cooking until the bottom of the rice is browned and fragrant about 10 minutes. Remove from heat and cool 5 to 10 minutes. Season with salt and pepper sprinkle parsley over the paella and garnish with lemon wedges. Serve with baguette slices.