Preheat the oven to 375 degrees F.
In a large skillet, heat 2 tablespoons olive oil. Add the onion and potatoes and toss to coat. Place it in the oven and roast until golden and tender, about 30 to 40 minutes.
In a medium saucepan, add sugar, vinegar and blood orange juice and bring to a boil. Reduce by 1/2 and set aside.
In a very large saute pan over medium-high heat, add 4 tablespoons butter and 2 teaspoons of oil. Season the fish with Essence, salt and pepper. Place fish in pan and cook until browned. Turn fish and repeat on the other side for the same amount of time.
Place the pea shoots in a bowl. Toss with some extra-virgin olive oil and season with salt and pepper.
To plate, place potatoes on the bottom of the each plate and top with 1 fillet. Place a mound of pea shoots on each fillet. Drizzle gastrique around the plate and garnish with blood orange slices.