- Portion size 6 servings
Preheat oven to 375°F (190°C).
Grease 13- x 9-inch (3 L) glass baking dish. Slice English muffins in half horizontally; spread lightly with mustard. Place half of the muffins, cut side up, in dish. Top with ham. Slice each piece of cheese in half diagonally; place 1 triangle over each piece of ham and set aside remaining cheese in refrigerator. Top with remaining English muffin halves, cut side up, and tomato slices.
Separate 3 of the eggs, reserving yolks in small bowl; cover yolks with plastic wrap and set aside in refrigerator for sauce. Whisk egg whites with remaining eggs, the milk, salt and pepper; pour over muffins. Cover and refrigerate for at least 4 hours or for up to 12 hours.
Using turkey baster or spoon, baste English muffin slices with some of the egg mixture. Arrange reserved cheese on top. Bake in centre of oven for 45 to 50 minutes or until golden and egg mixture is just set. Sprinkle with onion.
Meanwhile, in small heavy saucepan over medium-low heat, whisk together reserved egg yolks, 3 tablespoons (50 mL) water and the pepper; cook, whisking, for about 5 minutes or until pale and thick enough to coat back of spoon. Remove from heat. Whisk in butter and juice. Serve warm with strata.