Add your herbs, seasonings, tomato puree and paste plus, 1 cup seafood stock to pot. Mix well. Simmer down for 10 minutes or until your sauce thickens a bit. You'll want your sauce to be hearty and viscous enough to support your plump shrimp. But, thin enough to saturate your rice. If too thick, add additional seafood stock. In the end, if you want your sauce thicker - mix 2 tbs corn starch to 1 tbs water. Mix well and slowly add this slurry to your boiling sauce. It'll thicken up as it simmers so go slow.