Pat your protein dry with a paper towel; season with salt and pepper. (If using sausages, do not season with salt and pepper; instead, pat dry, then prick in a few places with a fork if desired.)
In a large frying pan over medium-high heat, warm 1 to 2 teaspoons oil until hot but not smoking.
Sausages:
Add the sausages and cook, turning occasionally, until browned and cooked through, 10 to 12 minutes. Transfer to a cutting board to rest for 5 minutes, then cut on the diagonal into ¼-inch-thick slices. Do not clean the pan.
Chicken:
Add the chicken and cook, turning occasionally, until lightly browned and cooked through, 4 to 6 minutes per side. Transfer to a cutting board to rest for 5 minutes, then cut into ¼-inch-thick slices. Do not clean the pan.
Steaks:
Add the steaks and cook, turning frequently, until well browned and medium-rare, 8 to 12 minutes. Transfer to a cutting board to rest for 5 minutes, then cut into ½-inch-thick slices. Do not clean the pan.
Pork chops:
Add the pork and cook, turning frequently, until browned but still faintly pink within, 8 to 10 minutes. Transfer to a cutting board to rest for 5 minutes, then cut into ½-inch-thick slices. Do not clean the pan.
Plant-based chicken:
Add the plant-based chicken and cook, turning occasionally, until browned and heated through, 4 to 6 minutes. Transfer to a plate. Do not clean the pan.
While your protein is cooking and resting, prepare the vegetables and assemble the skewers.