Preheat oven to 425°F with a rack in the center. Finely chop 2 teaspoons of garlic. Trim celery, then cut into ¼-inch pieces. Halve bell pepper, discard stem and seeds, then cut into ¼-inch pieces. Cut onion into ¼-inch pieces.

Heat 1 tablespoon of neutral oil in a medium ovenproof pot over medium-high. Add 10 oz grass-fed ground beef and cook, breaking up into smaller pieces, until browned, about 5 minutes.

Add onions, celery, and bell peppers to pot with beef. Season with a generous pinch each of salt and pepper. Cook, stirring, until veggies are softened and just starting to brown, and beef is cooked through, 5-7 minutes.

To pot, stir in half of the garlic, all of the ¼ oz Cajun seasoning, and ¼ teaspoon each of salt and sugar; cook until fragrant. Add 5 oz white rice and stir until combined. Add 1¼ cups water and bring to a simmer. Remove from heat, cover, and transfer to center oven rack. Bake until rice is tender and liquid is absorbed, 18-22 minutes.

Meanwhile, coarsely chop ¼ oz fresh parsley leaves and stems. In a small bowl, whisk to combine 2 (1 oz) mayonnaise, remaining garlic, and ½ teaspoon vinegar. Season to taste with salt and pepper.

Remove rice from oven and allow to rest, covered, about 5 minutes more. Fluff dirty rice with a fork and season to taste with salt and pepper. Garnish with parsley and serve with aioli on the side. Enjoy!