In a medium pot, combine the rice, 1 ¼ cups water (double for 4 portions) and ⅓ of the spice blend; bring to a boil. Reduce the heat, cover and let simmer, 17 to 20 minutes, until the rice is tender and the water has been absorbed. Remove from the heat and let sit, covered, for 5 minutes. Fluff the cooked rice with a fork and set aside in a warm spot.
While the rice cooks, small-dice the cucumbers and tomatoes; combine in a bowl. Mince the garlic. Cut off and discard the root end of the scallion; thinly slice, separating the white bottoms and green tops. Pick the dill fronds off the stems; roughly chop the fronds.
In a large bowl, combine the ground beef, garlic, ½ the white bottoms of the scallion and a drizzle of olive oil; season with the remaining spice blend and S&P. Gently mix to combine. Using your hands, form the mixture into 8 meatballs (double for 4 portions) about the size of a golf ball. In a medium pan, heat a drizzle of oil on medium-high. Add the meatballs* and cook, partially covered, turning occasionally, 9 to 11 minutes, until fully cooked and browned on all sides.
While the meatballs cook, in a medium bowl, combine the yogurt and avocado purée; season with S&P to taste. Stir until incorporated.
To the bowl of cucumbers and tomatoes, add the red wine vinegar, ½ the dill, as many of the remaining white bottoms of the scallion as you’d like and 1 tbsp olive oil (double for 4 portions); season with S&P to taste. Toss well.
On a large serving platter, spread ½ the avocado tzatziki in a circular motion. Top with the spiced rice, finished meatballs and chopped salad. Garnish with the remaining dill and as many of the green tops of the scallion as you’d like. Serve the remaining avocado tzatziki on the side. Bon appétit!