Shrimp, Corn, and Tomato Salad

This is spicy from the ginger, and a wonderful summer salad.  I broiled the whole thing--over cooked the shrimp a bit, so I would do 2 minutes, twirl the pan 180 degrees and another 2 minutes, or as described by the great Yoam Ottolenghi below.  Delicious!

1 lb. shrimp. shelled
1 tsp olive oil
Salt
1 small red onion, sliced or wedged
1 c. frozen sweetcorn, defrosted
2/3 c.  cherry tomatoes
1 tbsp picked marjoram (or oregano)
For the ginger, lime and sriracha dressing
3/4"  piece fresh ginger, peeled and finely chopped
1 tbsp sriracha
1½ tbsp olive oil
Finely grated zest of 1 lime (1 tsp), plus 1½ tbsp lime juice
¼ tsp sugar

In a small bowl, mix the dressing ingredients and an eighth of a teaspoon of salt.
Put a char-grill on a high flame and ventilate the kitchen. While it’s heating up, mix the prawns with the olive oil and an eighth of a teaspoon of salt. Griddle the onion wedges for five minutes, turning them every so often, until charred and cooked, but still with some bite. Transfer to a large bowl, then grill the corn for two minutes, until charred. Add to the onion bowl, then grill the tomatoes for three minutes, turning regularly, so they’re charred all over, and add to the bowl. Griddle the prawns for four minutes, turning them halfway, until charred and cooked through. Add to the bowl with the marjoram and dressing, toss gently, and serve at once.