Place the salmon on a plate and add the lime juice, garlic cloves, salt and pepper and let it sit for about 20 minutes.In a large pan over medium-high heat, warm the olive oil.
Place the salmon in the pan and cook until golden brown underneath, about 2 minutes.Turn the salmon over and continue cooking until golden underneath, about 2 minutes more for medium-rare, or until done to your liking.
Transfer the salmon to a platter, season with salt and cover with aluminum foil.To make the sauce:In a small saucepan over medium heat, melt the butter.
Add the onion and sauté until the onion is tender, about 3 minutes.
Add the tangerine juice, honey and tangerine zest and bring to a boil. Reduce the heat to low and simmer, stirring occasionally, until the mixture thickens, about 5 minutes.In a small bowl, stir together the cornstarch and water until the cornstarch dissolves.
Whisk the cornstarch mixture into the sauce and simmer until the sauce thickens, 1 to 2 minutes. Use immediately.