Rinse both rices together in a sieve. In large saucepan, combine rice, 1/2 teaspoon salt, oregano, thyme and 3 1/2 cups water. Cover and bring to a boil, then reduce heat to low and simmer until rice is tender and water is absorbed, about 45 minutes.

Preheat oven to 350°F Spread pecans in small baking pan and bake until toasted and fragrant, stirring once, about 7 minutes. Set aside to cool.

In large shallow serving bowl, whisk together vinegar, oil, remaining salt, pepper and cayenne. Add scallions, tomatoes, celery, bell pepper, currants and parsley and mix well.

When rice is done, remove from heat and let stand, covered, 5 minutes. Fluff with a fork and stir into vegetable mixture. Chill at least 15 minutes.

Just before serving, stir in toasted pecans and garnish with avocado slices.