Preheat the oven to 400°F and line a sheet pan with parchment paper.
Pat salmon dry and place on the pan. Drizzle with olive oil, sprinkle taco seasoning evenly, and season with salt and pepper.
Bake for 12–15 minutes, until the salmon flakes easily with a fork. Let cool on the pan for 20–25 minutes before handling.
Meanwhile, make the black bean salsa: In a large bowl combine red bell pepper, jalapeños, black beans, corn, green onions, and cilantro. Add lime juice, olive oil, and minced garlic; toss to coat and set aside.
If needed, cook brown rice according to package directions (a rice cooker helps for batch cooking).
Once cooled slightly, flake the salmon into large chunks with a fork.
Portion into four containers: about 1/2 cup rice on the bottom, a generous scoop of black bean salsa, and a portion of flaked salmon on top. Add avocado only to containers you’ll eat within 24 hours and squeeze lemon juice over it to slow browning.
Seal, label with today’s date, and refrigerate. Store salsa separately if possible for best texture by days 3–4.