This appears to be a Japanese pickle mixture, made with daikon radish amount other things, called Furkujinzuke.
Fukujinzuke is a mixture of Japanese radish (daikon), lotus root, cucumber and eggplant which are preserved in a soya sauce and sweet cooking wine (mirin) base. The sweet brown or red relish is served as a garnish to Japanese curry (kare raisu)....
Based on the concern of ingredients:
Gluten free, Keto, Vegan, Vegetarian, Non-vegeterian, pescatarian, Eggeterian etc.
Based on types of cuisine:
Continental, Italian, Thai, Mexican, Burmese, Lebanese etc.
Based on cooking techniques:
Barbeque, Baked treats, Let's steam, Straight from grill, Stir fries etc
Based on the dishes:
Salad station, wrap &...
My best guess based on your photo is that it's kabocha (aka Japanese pumpkin)
But squashes also hybridize pretty easily, so far as I know, so it could be a random hybrid rather than an established variety. Possibly one derived from kabocha or acorn squash.
If you grew this from seed saved from last year's garden squash, it could be that ...