Before starting, preheat the oven to a high broil and wash and dry all produce. Add 6 cups water and 2 tsp salt in a medium pot (NOTE: same amount for 4ppl). Cover and bring to a boil over high heat. Peel, then cut sweet potatoes into 1-inch pieces. Thinly slice chives. Trim beans. Pat pineapple dry with paper towels, then cut into 1/4-inch slices.
Add sweet potatoes to the pot of boiling water. Cook, uncovered, until fork-tender, 12-15 min.
While sweet potatoes cook, pat ham dry with paper towels. Add ham on a foil-lined baking sheet. Top with pineapple slices and sprinkle over 1 tbsp sugar (dbl for 4ppl). Broil in middle of oven, until ham is warmed through** and pineapple is golden-brown, 10-12 min.
While ham cooks, heat a large non-stick pan over medium-high heat. When hot, add 1/2 tbsp oil and 1 tbsp butter (dbl both for 4ppl). Stir together, until butter melts, 30 sec. Add beans and 1 tbsp water (dbl for 4ppl). Season with salt and pepper, then stir together. Cover and cook, stirring occasionally, until tender, 5-6 min.
When sweet potatoes are done, reserve 1/4 cup starchy water (dbl for 4ppl), then drain and return potatoes to the same pot. Using a masher, mash in reserved starchy water, chives and 1 tbsp butter (dbl for 4ppl) until smooth. Season with pepper.
Divide pineapple ham, sweet potato mash and beans between plates. Serve with mustard on the side, for dipping.