Toss cubed salmon in cumin and chili powder. Set aside. Heat large skillet over medium and cook yellow onion 2 minutes, until it begins to soften. Turn heat up to medium high. Add salmon to skillet. Lightly sear salmon cubes for about 2-3 minutes, turning gently (don't break the salmon into pieces!). IMPORTANT: Do not over cook the salmon. This juicy recipe will keep steaming the salmon. The salmon should still be firm in the middle of the cube when you proceed to the next step. Return heat setting to medium. Add canned tomatoes and chilies, cilantro and green onions. Gently incorporate and heat through. Squeeze quartered limes over the salmon mixture, give it a quick stir, and plate up the salmon (I usually drain a little liquid off at this point). Serve with warm flour tortillas, quality salsa, sour cream, sliced avocado, and crisp romaine lettuce.