Preheat grill on high for 5-10 minutes.
Thaw and cut bison sirloin steaks into 1 inch pieces, place in bowl and set aside.
In large bowl combine olive oil, vinegar, garlic, black pepper, oregano, basil, thyme and seal salt to make marinade. Add vegetables to marinade and toss to coat. Assemble vegetable skewers, alternating vegetables. Continue until all vegetables are gone.
Add bison sirloin to remaining marinade left over in the mixing bowl and toss to coat. Assemble bison skewers with remaining skewers.
Place vegetable skewers on the well-heated grill 2-3 minutes before adding the bison skewers, they will take longer to cook.
Turn vegetable skewers over once and then add bison skewers to the grill. Cook for about 3-4 minutes, turn bison skewers and cook an additional 3-4 minutes or until done (8-11 minutes total cooking time).
Preheat oven to 400°F.
Toss butternut squash with 1 tablespoon olive oil and sprinkle with salt and pepper.
Roast in preheated oven for 20 minutes on a sheet pan.
Turn squash over, add tomatoes. Continue to roast until soft and golden brown, about 20 minutes more.
Combine prepared couscous and remaining ingredients in mixing bowl and toss. Chill for 4 hours and serve.
*Can be made 4 hours ahead. Let stand at room temperature. Mix well before serving.