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Bring an 8-quart pot of water to a boil. Rinse and drain beans and pick off dry ends with your thumb nail. When water boils, place a large bowl of ice water on your counter, add some salt to the pot and stir in the beans. Boil until just crisp tender, about 3 minutes (avoid overcooking). Drain beans and immediately plunge them into the ice water. This completely stops the cooking process so the bright green color and crisp texture is retained. (If baby beans are unavailable, use regular green beans and blanch until they reach the desired texture, about 6 minutes.) See video on Blanching Vegetables, for more information.
Cut peeled onion in half through the stem end and slice each half into very thin wedges. Separate each wedge into strips.
Melt butter or heat the olive oil in a 12-inch, deep-sided skillet over medium-high heat. When hot, add poached garlic and cook, over medium heat, stirring constantly, until the garlic becomes golden. Use a slotted utensil to remove the garlic and set this aside, for now. Increase the heat to high and add the onions to the skilled and cook, until fragrant and tender, but not brown, about 10 minutes, stirring often. Add red pepper strips and cook 3 to 5 minutes more. Raise heat to medium-high, add string beans and toss to combine. Cook until almost tender, then add the minced garlic, if using, and continue to cook the beans until tender and some of the edges are a bit caramelized, about 5 minutes, stirring and tossing frequently.
Turn into a serving bowl and add grated Parmesan cheese, if using. Grind on some fresh pepper and sprinkle lightly with coarse salt, if desired. Serve hot.
Here are some easy additions and combinations to try with sautéed green beans:
Blanch and refresh the beans as directed before sautéing. Sauté string beans in hot butter or olive oil and when hot throughout but still crisp, add 1/2 cup toasted pine nuts and 1/2 cup freshly grated Parmesan cheese or (for a sharper flavor) grated Pecorino cheese. To toast pine nuts, place on a shallow baking sheet and bake at 350o F until golden but not scorched, about 10 minutes. Shake the pan occasionally while toasting. Be careful, once the nuts become fragrant, they're just about done--this is true when toasting all nuts.
Thinly slice 5 cloves garlic. Sauté very slowly in 4 tablespoons melted butter or fruity olive oil until tender and lightly golden, 3 to 5 minutes. Remove garlic with a slotted spoon and reserve. Add blanched beans to pan and cook briefly, just until tender. Toss with the sautéed garlic adding freshly ground black pepper to taste.
Heat 1/4 to 1/3 cup of very fragrant peanut oil over medium-high heat and sauté 2 teaspoons peeled, minced fresh ginger root, 2 cloves minced garlic and blanched baby beans. When hot throughout, stir in 1/4 cup pan toasted sesame seeds. Cook 1 minute over high heat then drizzle on 1 tablespoon of dark (toasted) sesame oil. To toast seeds, place a dry skillet over medium heat and when hot, add seeds. Stir constantly as seeds become golden, about 2 minutes. Remove from skillet to avoid scorching.