Preheat a Dutch oven or heavy deep skillet over medium high. Squeeze sausage from casing into pan, crumbling it into small pieces. Add onion and cook until chorizo is browned around edges and onions are translucent, about 5 minutes. Stir in garlic, rice, sun-dried tomatoes, smoked paprika and oregano. Cook, stirring constantly, until rice is toasted and aromatic, 1 to 2 minutes. Stir in broth and cover pan. Reduce heat to low and cook for 20 minutes, until rice is just tender. Remove from heat and let sit for 5 to 10 minutes, still covered, to allow rice to fully absorb liquid. Remove cover, add spinach and toss to combine. Serve immediately.