Potato and Spring Vegetable Tart from Vedge by Rich Landau and Kate Jacoby

Ingredients

• 3 teaspoons salt
• 1 cup vegan mayo
• 1 tablespoon vegan shortening, cold
• 1 tablespoon vegan butter, cold
• 1 tablespoon Dijon mustard
• 1 tablespoon freshly squeezed lemon juice
• 1 cup all-purpose flour, plus more for dusting
• 4 ounces arugula
• 2 cups peeled, diced Yukon gold potatoes
• 3 tablespoons olive oil
• 2 cups shelled English peas
• 2 tablespoons chopped fresh tarragon
• ½ teaspoon freshly ground pepper
• 1 cup thinly sliced leeks