Preheat oven to 450F or 425F convection. Line a baking sheet with parchment.
In a medium pot over high heat, add the farro and enough water to cover by at least 2-inches. Bring to a boil, then reduce heat to low and simmer until cooked through, about 20-30 minutes. Drain and set aside.
In a small-medium pot, mix together the maple syrup, soy sauce or tamari, vinegar, miso, and red pepper flakes (if using). Use a fork to mash and mix the miso paste in (it’s okay if it’s a little clumpy).
Add brussels to the baking sheet along with 1 tablespoon oil and ¼ teaspoon salt. Toss to coat. Make four spaces amongst the brussels for the salmon and place the salmon fillets in each spot (see photos). Brush each fillet with the maple soy glaze. Bake for 10-15 minutes, or until salmon is cooked through and brussels sprouts are charred (don’t be afraid to get a nice char!). If salmon is cooked before brussels start to char, just remove the salmon and keep roasting the sprouts.
Simmer the glaze gently for about 7 minutes, or until reduced to about ¼ cup. Remove from heat and stir in the garlic. Transfer to a bowl to cool a bit (it will get thicker as it cools).
Brush each salmon fillet generously with the glaze. Add farro, salmon and sprouts to your plate.
Drizzle a small amount of glaze over the farro and sprouts (it is pretty sweet so don’t overdo it). Top with a very generous squeeze of lime (two juicy wedges worth!), green scallions, and toasted nuts.