I don't remember where I got this recipe from originally, but it's my go-to summer salad — easy, tastes good, and it feels fun. A friend made it recently and said they really liked it, so I thought I'd share it. Hope you like it too!
Bring a saucepan of water to boil. Put the potatoes in with some salt for ~10 minutes until they're cooked through. Meanwhile, heat some oil in a frying pan over medium heat and fry the onions until they're golden.
Once the potatoes are cooked, drain them and set them to one side. In the frying pan, add the garlic to the onions and stir until fragrant. Turn the heat down low and add the drained potatoes. Add the vegan mayo a tablespoon at a time, stirring continuously until the texture looks right to you. The amount of mayo you need will vary depending on number and size of potatoes you used, but it'll probably be 3-4 tablespoons.
Add half a tablespoon or so of the wholegrain mustard, salt and pepper to taste, and stir everything through. Take off the heat and serve.
Depending on the mayo you use this can be quite rich, so it goes great with anything charred, citrusy or spicy. Have some fun with it: my friend threw some capers in at the end, worked great.