In a small heavy saucepan, bring the rice, 1½ cups water and a pinch of salt to a boil over high heat. Reduce the heat to medium-low, cover, and gently simmer for about 15 mins or until the water has been absorbed and the rice is tender. Don’t stir the rice during cooking, as this can release starches that will lead to sticking. Fluff the rice with a fork and let stand, covered, for 5 mins. Spread the rice over a baking tray and cool completely.
Meanwhile, preheat barbecue on medium heat. Coat the salmon with 1 tbs of the olive oil and season with salt and pepper. Barbecue the salmon for about 3 mins each side or until char marks have formed on the outside and the salmon still has a rosy centre.
In a small bowl, combine the lemon juice, vinegar, and the remaining 3 tbs olive oil and whisk to blend. Season the vinaigrette with salt and pepper.
Barbecue the corn, turning as needed, for 8 mins or until nicely charred and heated through. Cut the corn kernels off the cob and transfer to a large bowl. Stir in the cooked rice, coriander, chives, jalapeño and 3 tbs of the vinaigrette. Season with salt and pepper.
Spoon the rice salad into a large serving bowl. Scatter the avocado over the rice. Tear the salmon into large pieces and arrange in the bowl. Serve the mixed greens on the side and drizzle the remaining dressing over the greens and the salmon.