Cheesy onion quiche

For the sauce:
1 cup red bell pepper
1/4 cup mayonnaise
3 tablespoons crushed walnuts
2 teaspoons tomato paste
1 teaspoon minced garlic
1/4 teaspoon kosher salt
1/4 teaspoon freshly ground black pepper
For the filling:
4 tablespoons unsalted butter, cut into four pieces
1 cup finely chopped red onion
3 large eggs
3/4 cup heavy cream
1 -1/2 cups grated Jarlsberg, Swiss, or Gruyere cheese
3 tablespoons finely chopped fresh chives
1/4 teaspoon Tabasco sauce
1/4 teaspoon kosher salt
1/4 teaspoon freshly ground black pepper
1 uncooked pie crust (9 inches)

1. To make the sauce: Grill the bell pepper over Direct Medium heat until the skin is evenly charred on all sides, 10 to 12 minutes, turning every 3 to 5 minutes. Remove the pepper from the grill and place in a paper bag; close tightly. Let stand 10 to 15 minutes to steam off the skin. Remove the pepper from the bag and peel away the charred skin. Remove the pepper from the bag and peel away the charred skin. Cut off the top and remove the seeds. Coarsely chop the pepper and put in a food processor. Add the remaining sauce ingredients and process until smooth. Pour into a small serving bowl, cover and refrigerate until ready to serve.
2. To make the filling: In a medium sautй pan over medium heat, melt the butter. Add the red onion and cook, stirring occasionally, until translucent, 3 to 5 minutes. Transfer to a medium bowl and allow to cool for a few minutes. In a small bowl whisk the eggs and cream together and add to the butter-onion mixture. Add the remaining filling ingredients and mix thoroughly.
3. Line a 9-inch metal pie tin with the crust. Pour the filling into the crust. Grill over Direct Medium heat until the edges of the crust and the filling begin to turn golden brown, about 15 minutes, then continue cooking over Direct Low heat until the filling is no longer wet in the center, about 15 minutes more. Remove from the grill and allow to cool for 10 to 15 minutes. Serve with the sauce.