To prepare the sauce, heat 1 Tbsp. olive oil in saucepan over medium heat. Sauté 1 c. of the onion and 3 cloves of garlic in oil for 5 - 7 minutes or until soft.
Add dried chilies and sauté 3 minutes more.
Stir in tomatoes and water. Season with salt and pepper and simmer 10 - 15 minutes. Remove from heat, cool 5 minutes, then purée in blender or food processor until smooth.
To prepare the enchiladas, preheat oven to broil.
Place poblano chiles on baking sheet and broil 15 - 20 minutes or until blackened on all sides, turning often. Cool in covered bowl, then peel off skins and remove seeds. Chop chiles into 1/4-in. pieces.
Preheat oven to 375°F/190°C
Heat 1 Tbsp. olive oil in skillet over medium heat. Sauté remaining onion and garlic in oil for 3 - 5 minutes or until soft.
Transfer to mixing bowl and add queso fresco, 1/2 c. Monterey Jack cheese, cilantro and chopped chiles.
Spread tortillas on baking sheet. Warm 3 minutes in oven to soften.
Spread 1 c. sauce over bottom of 13x9-in. baking dish. Divide cheese mixture among tortillas, and roll loosely. Place filled, rolled tortillas in baking dish. Top with remaining sauce and sprinkle with remaining Monterey Jack cheese.
Bake 15 - 20 minutes or until sauce is bubbly and cheese is melted. Sprinkle with cilantro before serving.