Melt butter in 10-inch nonstick skillet until sizzling; add onion. Cook over medium heat until onion is softened - 3 to 5 minutes. Stir in chiles.
Meanwhile, combine eggs and water in medium bowl. Beat with wire whisk until well mixed. Pour eggs into skillet; sprinkle with sausage. Cook over medium heat, gently lifting portions with spatula so uncooked portion flows underneath, until eggs are set - 3 to 5 minutes.
For each serving, place 1/2 slice cheese in center of warm tortilla. Spoon 1/3 cup eggs over cheese; spread with 1 Tbsp picante sauce. Sprinkle with 1 tsp cilantro; top with 1/2 slice cheese. Fold edges over filling, overlapping slightly. Roll up tortilla from bottom to enclose filling. Repeat with remaining ingredients.Servings: 4 to 6