01 - Boil tomatoes in a pot of water for 5-6 minutes until skins split. Drain and transfer to blender with garlic, onion, serrano chilies, cumin, salt, and pepper. Blend until completely smooth.
02 - Heat 2 tablespoons oil in a skillet over medium heat. Pour in blended tomato sauce and simmer for 7-10 minutes, stirring occasionally until slightly thickened. Adjust seasoning as needed.
03 - Heat small amount of oil in separate skillet over medium heat. Lightly fry tortillas one at a time for approximately 10 seconds per side just until soft and pliable. Drain briefly on paper towels.
04 - Dip each prepared tortilla into hot tomato sauce, coating both sides thoroughly. Place on plate, fill with cheese, and fold in half or roll up. Continue process until all tortillas are assembled.
05 - Arrange 3 entomatadas on each serving plate. Drizzle with additional tomato sauce, sprinkle with extra cheese, diced onion, and fresh cilantro. Top with dollop of sour cream or crema.