Add grapeseed oil to skillet and let the pan get piping hot.
Add salmon and cook 4 minutes on each side. Remove from pan.
Add remaining 1 tablespoon butter to pan and melt. Add garlic to the melted butter and sauté for a minute.
Add wine and bring the mixture to a boil, scraping any browned bits off of the bottom of the pan. Cook until liquid almost evaporates.
Add 3/4 cup broth to the pan along with the lemon juice and cook for a few minutes.
Mix the cornstarch with the reserved 1/4 cup stock/broth, and mix to combine evenly. Pour the mixture into the pan, stirring to create a sauce for a few minutes.
Add capers and place salmon fillets back into the pan.