Finely chop the tomatoes and place in a sieve over a bowl to drain. Set aside.
Trim the asparagus by removing the bottom inch of the stem. Cut them into one-inch lengths and place in a steamer basket.
Steam for 4-5 minutes, until they are bright green and crisp-tender when pierced with the tip of a sharp knife. Asparagus can overcook quickly, so keep an eye on them. Once cooked, place in a large bowl and set aside.
Place the Greek yogurt, apple cider vinegar, and ketchup in a bowl and whisk well.
In a small bowl, mix the egg white powder and konjac flour together well.
Quickly whisk the egg white mixture into the yogurt, then whisk in the fresh chopped mint.
Add the drained tomatoes to the large bowl with the asparagus, add the prawn pieces, and then add the yogurt mixture.
Carefully stir all the ingredients together until completely combined.
Take a keto or low carb taco or tortilla of your choice, pile the salad inside and serve.