Slice the kielbasa into 1/2-inch thick rounds and set aside. Peel and devein the shrimp, patting them dry with paper towels—this helps them cook more evenly in the foil packet. Dice the onion, green bell pepper, and celery into the specified sizes, mince the garlic, and chop the fresh parsley. Having everything prepped and ready ensures smooth assembly and prevents the proteins from sitting too long before cooking.

Preheat your grill or oven to 400°F. While it heats, combine the Cajun seasoning, dried thyme, Worcestershire sauce, salt, and cracked black pepper in a small bowl to create a unified seasoning blend. This ensures the spices distribute evenly throughout the jambalaya rather than clumping in one spot.

Spray or lightly oil 5 sheets of heavy-duty foil (about 12x18 inches each) and lay them shiny-side up on your work surface. On each foil sheet, arrange the ingredients in layers: start with the diced vegetables (onion, bell pepper, celery), then distribute the kielbasa slices evenly, followed by the shrimp. Sprinkle the seasoning blend from Step 2, the minced garlic, and fresh parsley over each packet. I like to organize the proteins on top of the vegetables so they steam gently above the aromatics—this prevents them from overcooking while the vegetables soften below.

To each foil packet, add 1/4 cup of instant rice, 1/4 cup of low-sodium chicken broth, and 1/4 cup of the diced tomatoes (about 3-4 tablespoons per packet). The rice will absorb the broth and tomato juices as everything steams, creating a cohesive one-packet meal with proper texture and moisture.

Fold each foil sheet in half over the ingredients, then crimp the edges tightly to create a sealed packet—this traps the steam inside, which both cooks the ingredients and infuses them with flavor. Place the sealed packets directly on the grill grates or on a baking sheet in your preheated 400°F oven. Cook for 25-30 minutes until the shrimp are pink and cooked through and the rice has absorbed the liquid. I always make a small slit in one packet after 20 minutes to peek inside and check that the rice is softening properly.

Carefully remove the hot foil packets from the grill or oven using tongs or an oven mitt—the steam inside will be very hot. Let the packets rest for 2-3 minutes before opening them. This brief rest allows the flavors to meld slightly and prevents the steam from escaping immediately. Open each packet by carefully peeling back the foil, working away from your face to avoid steam burns. The jambalaya is ready to serve directly from the packet—simply give it a gentle stir and adjust seasoning with additional salt or Cajun seasoning if needed.