Aussie steak sandwich

Name: Aussie steak sandwich
Prep time: 15 min
Cook time: 15 min
Total time: 30 min
Cuisine: Australian
Ingredients: 10.00 gm bush spice seasoning (see notes); 2.50 gm smoked paprika; 1 tsp finely grated lemon rind; 36.40 gm extra virgin olive oil; 2 garlic cloves, crushed; 4 x 150g beef sirloin or rump steaks; 2 red onions, sliced into rings; 1/2 pineapple, peeled, thinly sliced; 8 slices crusty sourdough bread; Olive oil cooking spray; 61.88 gm light whole-egg mayonnaise; 21.00 gm lemon juice; 225g can beetroot slices, drained; 4 butter lettuce leaves; 45.20 gm smoky barbecue sauce