My girls went through a 'hot dog jag'. Even though they are 2, I'd still follow the same principle as it was over within a couple of weeks. Offer what he likes, along with something questionable and perhaps something new. They demanded hot dogs so that's what they got with a slice of toast and apple for breakfast. I made ZERO issue out of it because as I'm learning children control eating, potty and sleep if you're not careful lol.
After a couple of days, they started picking at the rest of the stuff and then they started eating everything, then they quit asking for hot dogs altogether. They didn't starve, and I just went through a bunch of hot dogs. If he wants orange, give him orange plus blueberries and something else. At that age, I always liked serving cooked carrotts sliced thin lengthwise. It's a little messy at first but keep it fun and that pincer grip will come in nicely. Cut up bananas into thirds after you slice them, baby mum mums are good, toast fingers (cheese whiz will make them orange) etc.
HTH