1. Fill a large pot with water. Bring the water to a boil. Add the greens beans to the water. Cook, uncovered until bright green and crisp-tender (about 3 minutes or so). Drain and rinse with cold water until cooled. Drain well.
2. In a large skillet over medium heat, melt the butter and add cooking oil. Add mushrooms and cook uncovered until they just start browning .
Add the green beans and garlic to the mushrooms and cook for another 3-4 minutes or until green beans reach desired tenderness. We like ours to still have a nice crunch.
Season with salt and pepper. Remove from heat and serve.