In a blender or food processor blend the olive oil with the next 7 ingredients until emulsified; toss the lettuce leaves with about HALF of the vinaigrette and reserve the remainder to brush on the buns.
Grill tops and bottoms of the buns on a lightly oiled grill rack (about 2 minutes per side; transfer cut-sides up to a platter or plate.
Brush the cut sides of the top halves with remaining vinaigrette.
On the bottom halves divide/mound the coated lettuce leaves.
Cut the kielbasa sausage crosswise into 4 long sections, then half each section lenghwise (you may trim off the outside skin before grilling if desired).
Grill the sausage slices on a lightly oiled grill rack about 3-4 minutes turning over once during cooking.
Arrange 2 pieces of grilled sausage over the lettuce (2 pieces per sandwich) then top with sliced tomatoes (season the tomatoes with salt and pepper).