Preheat the oven to 425°F.
Line a baking sheet with foil, and place the salmon skin side down on the pan.
In a small bowl, mix the brown sugar, smoked paprika, ancho chili powder, onion powder, garlic powder, salt, and olive oil until combined.
Rub the seasoning blend evenly over the top and sides of the salmon.
Bake for 10 minutes, or until just cooked through, then broil on high for 2 minutes until the top is lightly crisp.
Remove the salmon from the oven, and let it rest for 5 to 10 minutes. Slice into portions, being careful not to cut through the skin, then peel the salmon right off.
Rinse the rice until the water runs clear. Add the rice and chicken stock to a pot, bring to a boil, cover, reduce the heat to low, and cook for 15 minutes. Turn off the heat, and leave the rice covered until ready to serve. Fluff with a fork before using.
In a bowl, combine the cucumbers, avocado, red onion, cilantro, lime juice, salt, and pepper. Toss gently, and adjust seasoning to taste.
To assemble the bowls, add rice, top with salmon and avocado cucumber salad, and finish with a drizzle of the sriracha lime sauce.