Preheat a medium cooking pan over medium-high heat.
Peel and devein shrimp. Mix shrimp with some Cajun seasoning.
Add some oil to the heated cooking pan and add shrimp. Sear shrimp on both sides until opaque. Take out shrimp and set aside.
Add sliced yellow onion to the pan and saute until transparent. Smash garlic and add it to the pan as well. Saute onion and garlic until fragrant and slightly browned.
Add broth and bring to boil. Lower heat to low/medium-low and add tomato sauce, salt, Cajun seasoning, and lemon juice.
Add quinoa, stir, cover and cook for about 15 minutes, until quinoa is just done.
Stir in chopped green onion and minced parsley. Add shrimp back to the pot. Cook just until shrimp is heated through again.