Get out your skillet and put about 1/2 inch of water in it, cover it, and bring to boil. While that works, pop the ends from the green beans (and cut into shorter lengths if you like).
Prep the garlic: mince one clove and peel and thinly slice the other. Chop up the green onions and serrano, if using.
Drop the beans into the boiling water in the skillet. Cover and set a timer for 1 minute. Drain in a colander.
Return the skillet to the stove and add half the oil over medium heat. Add sliced garlic and fry, turning, for about 45-60 seconds until golden. Remove from the oil.
Add remaining oil over med-high heat and add green beans. Stir and sear for about 2 minutes until beginning to blister.
Add green onion, minced garlic (and serrano) and cook another 30 seconds. Sprinkle with salt.