Parboil the green beans: To parboil the green beans, you'll need just four basic kitchen tools: a medium-large pot (like a Dutch oven or soup pot, 4-quart capacity is fine), a large work bowl, a mesh strainer, and a clean dishtowel or two. Fill the pot with 2 quarts water and 1 tablespoon coarse salt and bring it to a boil. Fill the work bowl mostly with ice and cover with cold water. Dump your prepped beans into the boiling water and cook for 4 to 5 minutes. Begin timing as soon as the beans are in the water; don't wait for it to return to a boil. And don't go anywhere- use your mesh strainer to transfer the veggies to the ice bath just as soon as the time's up. Let the green beans sit for a minute or two in the ice water to stop the cooking and cool down. Lift the beans (use your hands or the strainer again) out of the ice bath and let them drain well in one layer on a dishtowel (or paper towels). Store them in a shallow container (lined with paper towels to absorb any excess moisture), covered with a slightly damp paper towel or dishtowel. They'll keep in the refrigerator overnight. If you plan to use them right away, make sure they're very dry.

Make the sauce: In a small bowl, whisk together the orange juice, mustard, and brown sugar. In a large nonstick skillet, melt the butter over medium heat. Add the red-onion and pecans and toss to coat. Turn the heat to medium high and saute, stirring often, until the onions are very shrunken and many are browned (the pecans will be golden), 8 to 10 minutes. Add the beans in one layer over the contents of the pan and season with salt, a few grinds of pepper, and the thyme. Add the mustard mixture, immediately turn the heat to medium low (the sauce will begin to thicken), and stir vigorously (or use tongs) to toss and combine the beans with the sauce. Continue cooking to heat the beans through and to thoroughly coat them, 1 to 2 minutes.