Heat a large skillet over medium-high heat. Pour in olive oil, then mix in onion, garlic, and almonds. Saute until onions are translucent, about 5 minutes.
Stir in green beans and season with salt and pepper. Cover skillet with lid and cook for 3 minutes, stirring a few times so mixture doesn't burn. Transfer mixture to a shallow dish and place in refrigerator to cool. When cool, pack into a resealable bag.
At campsite, heat a skillet over the fire or camp stove, dump in contents of bag, and cook just until heated through.