• Zest the lime; cut the lime into wedges for garnish. [Zest 1 lime and cut into wedges; save the remaining lime for another use.]
• Coarsely chop the cilantro; set aside half for garnish.
• Cut a small corner from the ground turkey packaging and drain off any excess liquid. Transfer to a plate; pat dry with a paper towel.

In a large bowl, combine the meatball seasoning blend, ½ teaspoon [1 tsp] lime zest, and half the cilantro. Add the turkey, season with salt and pepper, and mix until just combined. Using wet hands, form the mixture into 1-inch meatballs.

In a large sauce pot over medium-high heat, warm 1 to 2 teaspoons oil until hot but not smoking. Add the meatballs and cook, turning occasionally, until lightly browned but not yet cooked through, 2 to 3 minutes per side. Transfer to a plate. Do not clean the pot. Meanwhile, prepare the remaining ingredients.

• Peel and finely chop enough shallots to measure ¼ cup [½ cup].
• Remove any coarse stems from the mustard greens; coarsely chop the greens.

In the same pot used for the meatballs, warm 1 to 2 teaspoons oil over medium-high heat until hot but not smoking. Stir in the shallots and cook, scraping up any browned bits from the bottom of the pot, until starting to soften, 1 to 2 minutes. Stir in the lemongrass paste and cook until fragrant, about 30 seconds.
Add the tomatoes, vegetable broth, and 1¼ cups [2½ cups] water, season with salt and pepper, and bring to a boil. Reduce to a simmer and add the meatballs, carrots, and greens (the greens in batches if needed). Cook, stirring occasionally, until the meatballs are cooked through and the carrots and greens are just tender, 5 to 7 minutes. Remove from the heat and season to taste with salt and pepper.

Transfer the soup to individual bowls. Garnish with the remaining cilantro and serve with the lime wedges.