Wash and dry all produce. Trim, then thinly slice scallions, separating whites from greens. Using a vegetable peeler, shave carrots lengthwise into thin ribbons. Using same peeler, shave zucchini lengthwise into thin ribbons.

In a large bowl, combine carrot ribbons, zucchini ribbons, 2 TBSP vinegar (we sent more), and 1 TBSP olive oil. Season with salt, pepper, and 1 tsp Southwest Spice. Set aside to marinate, stirring occasionally, until ready to serve.

Zest limes until you have 2 tsp zest; quarter limes. In a small bowl, combine sour cream, juice from 4 lime wedges, and lime zest (to taste). Season with salt and pepper.

Heat a large drizzle of oil in a large pan over medium-high heat. Add beef, chili powder, scallion whites, remaining Southwest Spice, salt, and pepper. Cook, breaking meat up into pieces, until browned and cooked through, 6-8 minutes. Drain off any excess oil from pan. Add stock concentrates, 1/3 cup water, and 2 TBSP butter. Stir until thoroughly combined and butter has melted.

Wrap tortillas in damp paper towels and microwave on high until warmed through, 1-2 minutes.

Fill tortillas with beef and marinated veggies. Dollop with lime crema. Garnish with scallion greens. Serve with remaining lime wedges on the side for squeezing over.