In a large resealable plastic bag, combine the first five ingredients; add swordfish. Seal bag and turn to coat; refrigerate for 30-45 minutes.
Drain and discard marinade. Using long-handled tongs, moisten a paper towel with cooking oil and lightly coat the grill rack. Grill swordfish, covered, over medium-hot heat or broil 4 in. from the heat for 5-7 minutes on each side or until fish just turns opaque.
Cut zucchini and yellow squash lengthwise into 1/4-in. slices, then widthwise into 3-in. pieces. In a large skillet, saute the onions and rosemary in oil for 1-2 minutes or until onions are tender. Add squash; saute for 5-6 minutes or until crisp-tender. Add potatoes and tomatoes; cook just until heated through. Sprinkle with salt and pepper; toss to coat. Serve with swordfish.