Preheat oven to 400°F/200°C.
Mix together sesame oil, coconut aminos, fish sauce, ginger, garlic, sweetener, lime zest and juice, and cayenne pepper (to taste).
Add salmon and marinate for at least 15 minutes, but preferably for 2 hours or overnight.
Lightly oil a large piece of foil (about twice the size of your salmon filets).
Place salmon skin side down over the foil and add only a couple of spoonfuls of the teriyaki marinade (reserve the rest).
Fold foil to create an envelope (or whatever shape you desire, as long as it's sealed closed).Place foil packet on a rimmed baking sheet and bake until just cooked through, 16-20 minutes (cooking times will vary depending on the thickness of your salmon).
Be careful when opening foil envelope, as scalding steam will be released.Add reserved teriyaki marinade to a small saucepan over medium/low heat, while salmon is cooking, and simmer for about 10 minutes.
Dissolve the arrowroot in water (i.e.
make a slurry), and whisk it into the saucepan.
Continue to simmer, whisking constantly to avoid lumps, until the sauce begins to thicken.
Adjust thickness to taste with more arrowroot or water, keeping in mind that the sauce will continue to thicken as it cools.
Remove from heat.
Change oven settings to broil, brush salmon with part of the teriyaki sauce and return to oven for 3 to 4 minutes.
Flake salmon with two forks (discarding the skin) and serve atop a bed of lettuce and cucumber.
Topped with teriyaki sauce, sesame seeds and plenty of limes.