Preheat oven to 400°F and grease a dark-rimmed sheet pan; no lining is necessary. Zest lime with zester to get 1/4 teaspoon zest and juice both limes to get 3 tablespoons lime juice. Set aside.
In a large bowl, combine all ingredients for the meatballs. Don’t overmix. Knead mixture until well combined. With wet hands, take about 1 tablespoon and 1 teaspoon (30 grams) of the mixture and roll it into a ball (see note 1). Place meatballs on the prepared sheet pan and spray them generously with cooking spray. Bake 15 minutes, then flip each meatball and bake for another 5–7 minutes or until nicely browned. Remove from oven and set aside.
In a large wide-mouth jar or large bowl, add carrots and radishes. Top with vinegar, sugar, and 1 teaspoon salt. Seal and shake well. Shake well or toss with tongs every 10–15 minutes while preparing the rest of the dish (see note 2).
Whisk all sauce ingredients together until smooth, including lime zest and lime juice. Season with a pinch of salt, cover, and chill in fridge until needed.
Butter buns and toast in a dry pan. Add sauce to both sides of bun. Top with a big scoop of pickled veggies, thinly sliced cucumbers, jalapeños, a few sprigs of cilantro, and meatballs. Sandwich together and enjoy promptly!
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Notes
Note 1: Use a cookie scoop or a food scale to measure out meatball portions for uniform size, ensuring they cook evenly. Tightly compress the meatballs to keep them from falling apart.Note 2: If you have the time, make the pickled veggies and sauce a day or two ahead. They’ll get more flavorful and it helps break up the cooking time!Nutrition Note: Nutrition information does not include the bun.Storage: These sliders are best enjoyed fresh. If you have leftovers, store slider components separately: meatballs in an airtight container in the fridge (3–4 days) or freezer (up to 3 months), pickled veggies in the fridge (5–7 days), sauce in the fridge (up to a week), and buns at room temperature (a few days) or in the freezer (up to 3 months). For best freshness and texture, assemble sliders right before serving.