Using the BBQ in the is heat wave is a nice alternative. The veggies are only on the grill for five minutes, so you'll barely break a sweat outside. You could use any coloured pepper and we've tried it with grilled onions too. It makes enough for 4 sandwiches, so you can half the recipe if there are only two of you. I've also saved the veggies and made a sandwich the next day with the cold leftovers.
2 red peppers
2 Tbsp olive oil
2 Tbsp lemon juice (divided)
2 tsp sriracha (divided)
1 tsp minced lemongrass
1/4 cup mayonnaise
Preheat BBQ on high. Slice zucchini lengthwise and cut peppers into quarters. Toss vegetables with olive oil, 1Tbsp lemon juice and 1tsp sriracha sauce. Grill veggies 3-5 min per side, until grill marks appear. Slice vegetables.
In a separate bowl, combine 1Tbsp lemon juice, lemongrass and 1tsp sriracha with mayonnaise. Can be made up to 5 days in advance.
Toast 8 slices of bread. Spread aioli on bread and pile grilled veggies on. Top with lettuce and enjoy!