Stir sour cream, 1/4 cup chives, milk, lemon juice and 1/4 teaspoon salt in a small bowl until combined. Set aside.
Heat oil in a large nonstick skillet over medium-high heat. Add zucchini, green beans and corn and cook, stirring, until beginning to brown, 6 to 8 minutes. Reduce heat to low; stir in ricotta, Monterey Jack, the remaining 1/4 cup chives, the remaining 1/2 teaspoon salt and pepper. Cook, stirring gently, until the cheese is melted, 1 to 2 minutes. Remove from the heat.
To roll crêpes, place one on a piece of parchment or wax paper (or leave it on the piece of plastic separating the crêpes in the package). Spoon one-fourth of the vegetable-cheese mixture (about 3/4 cup) down the center of the crêpe. Use the paper (or plastic) to help you gently roll the crêpe around the filling. Place the crêpe seam-side down on a dinner plate. Repeat with the remaining crêpes and filling. Serve each crêpe topped with 2 tablespoons of the reserved sauce and more chives, if desired.
Tips & Notes
Tips: To remove kernels, stand a cob on its stem end in a bowl and slice them off with a sharp, thin-bladed knife.
“Ready-to-use” crèpes are fast and convenient. Look for them in the produce section of the market or near refrigerated tortillas.