Wash the potatoes and place on a plate in the microwave. Microwave potatoes for 3 minutes. Turn potatoes and microwave again for 3 more minutes. Let potatoes cool down for 2 to 3 minutes. Peel potatoes and chopped in 1/2-inch pieces and set aside. Heat the oil in a large frying pan over medium heat. Add the cumin seeds, red crushed pepper, ginger, and chili and cook, stirring occasionally, until fragrant, about 1 minute. Add the frozen peas, coriander, turmeric, chili powder, and 1/2 teaspoon of salt to the frying pan and stir to coat. Cook for 5 minutes. Add the potatoes and 1/2 teaspoon salt, stir and cook for 5 more minutes. Add the lemon juice and garam masala stir well and set aside.
In a medium bowl mix flour, salt, and carom seeds. Add butter and water and mix well to make a firm dough. Knead the dough until smooth and roll into a ball. Divide the dough into 6 equal pieces. Roll each piece into a ball and roll out into a oval. Divide this oval into two equal semicircles with a knife. Brush the edges of the semicircle with a little water and form a cone shape, sealing the dampened edge by pressing tightly. Fill the cases of the samosa with filling mixture (until filing is level with sealed cone edge) and press the two dampened edges together to seal the top of the cone. Repeat until you have filled all of the samosas. Place the samosas in a baking sheet. Set aside.
Preheat oven to 400 °F. Mix the egg yolk and water together. Brush the samosas with the egg wash. Cook in the oven for 20 to 30 minutes.