Preheat the oven to 425°F. Line a large rimmed sheet pan with parchment paper if desired.
Add the cubed sweet potatoes to the sheet pan.
Drizzle with 2 tablespoons olive oil, then sprinkle with Tajín, garlic salt, and brown sugar.
Toss until the sweet potatoes are evenly coated, then spread them into an even layer.
Bake the sweet potatoes for 15 minutes at 425°F.
Remove the sheet pan from the oven and add the Trader Joe’s beef kebabs to the pan. If using sausage, cut it into pieces and add those instead.
Reduce the oven temperature to 350°F.
Return the sheet pan to the oven and bake for another 20 minutes, or until the sweet potatoes are tender and the meat is hot and cooked through according to its package directions.
While the sheet pan finishes cooking, make the green sauce. Add the cottage cheese, lemon juice, olive oil, water, garlic, parsley, dill, and kosher salt to a small blender or food processor.
Blend until completely smooth and creamy. Taste and add a little more water if you prefer a thinner sauce.
Make the tomato cucumber salad by combining the chopped tomato, cucumber, vinegar, olive oil, and a pinch of salt in a small bowl. Stir gently.
Divide the roasted sweet potatoes and beef kebabs among plates.
Serve with the tomato cucumber salad and a generous spoonful of green sauce.