Make the marinade: In a bowl whisk together 1 tbsp honey, juice of 1/2 lemon, 1/2 tsp garlic powder, and 1 tbsp reduced-sodium soy sauce. Add the 4 salmon pieces (14 oz total), turn to coat, cover and refrigerate up to 30 minutes, turning once after 15 minutes. Reserve the marinade.
Cook the farro: In a saucepan combine 1 cup pearled farro and 3 cups water. Bring to a boil over medium-high heat, cover, reduce heat to medium-low and simmer 15–20 minutes (or according to package) until tender. Drain any excess water and set the cooked farro aside, covered to keep warm.
Prepare the vegetable sauce: In a large nonstick skillet combine 2 tbsp soy sauce, 1 tbsp oyster sauce, the juice of the remaining 1 lemon, 1 clove crushed garlic, and 1 tbsp sambal chili paste. Heat over medium just until the mixture is combined and starting to steam.
Cook the vegetables: Add 7 oz sliced shiitake mushrooms, 1 tbsp finely minced fresh ginger, 1 cup snap peas, and 1/4 cup sliced scallions (from the 1/2 cup). Cook over medium heat, stirring occasionally, about 5 minutes, until the mushrooms have softened and the snap peas are tender-crisp.
Combine farro and vegetables: Add the cooked farro to the skillet with the vegetables, toss to coat and heat through 1–2 minutes. Remove from heat and keep warm.
Cook the salmon: Heat a nonstick skillet over medium heat and lightly spray with cooking spray. Remove the salmon from the reserved marinade (keep the marinade) and place the salmon in the skillet. Cook about 2 minutes per side, pour the reserved marinade over the salmon, reduce heat to low, cover, and cook 5 minutes more, until cooked through.
Serve: Divide the farro and vegetable mixture among plates, top each portion with a salmon piece, sprinkle the remaining 1/4 cup sliced scallions over the top, and finish with 1 tbsp black sesame seeds.