Combine tomatoes, stock, wine, 1 1/2 teaspoons vinegar, paprika, and 1/4 teaspoon salt in a blender; process until smooth. Transfer mixture to a small saucepan over medium-high heat; bring to a boil. Simmer 10 minutes, stirring occasionally; remove from heat.
Heat a nonstick skillet over medium-high heat. Add 1 1/2 teaspoons oil. Sprinkle salmon with 1/4 teaspoon salt and 1/4 teaspoon pepper. Add salmon to pan. Cook 4 minutes on each side.
Combine remaining 1 1/2 tablespoons vinegar, remaining 1/4 teaspoon salt, remaining 1 1/2 tablespoons oil, remaining 1/4 teaspoon pepper, cashews, and onions in a bowl; toss to coat.
Divide stock mixture among 4 bowls. Place 1 salmon fillet in each bowl; top fillets with cashew mixture.
Not only was this a very easy and fast recipe to make, it looked beautiful on the plate! The same and broth had unbelievable flavor and the vinegary topping added brightness. This dish was very elegant, I would serve this to guests.